Da qualche giorno mi si aprono pagine web all'improvviso... solitamente conteneti pubblicità (casinò hotel voli ecc.)
Ho gia fatto una scansione con CCleaner, poi come letto su vari siti ho scaricato HijackThis... ed ora eccomi qui a chiedere il vostro aiuto.
Grazie anticipatamente!

Logfile of Trend Micro HijackThis v2.0.4
Scan saved at 22.16.28, on 07/09/2010
Platform: Windows Vista SP1 (WinNT 6.00.1905)
MSIE: Internet Explorer v8.00 (8.00.6001.18943)
Boot mode: Normal

Running processes:
C:\Windows\system32\taskeng.exe
C:\Windows\system32\Dwm.exe
C:\Windows\Explorer.EXE
C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
C:\Program Files\TOSHIBA\Toshiba Online Product Information\TOPI.exe
C:\Windows\System32\igfxtray.exe
C:\Windows\System32\hkcmd.exe
C:\Windows\System32\igfxpers.exe
C:\Program Files\TOSHIBA\Power Saver\TPwrMain.exe
C:\Program Files\TOSHIBA\SmoothView\SmoothView.exe
C:\Program Files\TOSHIBA\FlashCards\TCrdMain.exe
C:\Program Files\Camera Assistant Software for Toshiba\traybar.exe
C:\Program Files\Microsoft Office\Office12\GrooveMonitor.exe
C:\Windows\system32\igfxsrvc.exe
C:\Program Files\AVG\AVG9\avgtray.exe
C:\Program Files\Windows Sidebar\sidebar.exe
C:\Program Files\TOSHIBA\TOSCDSPD\TOSCDSPD.exe
C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
C:\Program Files\Photo Toolkit\IvBar\phototoolkitmem.exe
C:\Program Files\Nokia\Nokia PC Suite 7\PCSuite.exe
C:\Program Files\Windows Live\Messenger\msnmsgr.exe
C:\Windows\system32\igfxext.exe
C:\Windows\system32\wbem\unsecapp.exe
C:\Windows\system32\wuauclt.exe
C:\Windows\system32\conime.exe
C:\Program Files\Microsoft Office\Office12\WINWORD.EXE
C:\Program Files\Microsoft\Office Live\OfficeLiveSignIn.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Program Files\OfferBox\OfferBox.exe
C:\Trend Micro\HiJackThis\HiJackThis.exe
C:\Users\User\Downloads\HiJackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.facebook.com/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant =
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = *.local
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
R3 - URLSearchHook: AVG Security Toolbar BHO - {A3BC75A2-1F87-4686-AA43-5347D756017C} - C:\Program Files\AVG\AVG9\Toolbar\IEToolbar.dll
O1 - Hosts: ::1 localhost
O2 - BHO: AcroIEHelperStub - {18DF081C-E8AD-4283-A596-FA578C2EBDC3} - C:\Program Files\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll
O2 - BHO: WormRadar.com IESiteBlocker.NavFilter - {3CA2F312-6F6E-4B53-A66E-4E65E497C8C0} - C:\Program Files\AVG\AVG9\avgssie.dll
O2 - BHO: Spybot-S&D IE Protection - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O2 - BHO: Search Helper - {6EBF7485-159F-4bff-A14F-B9E3AAC4465B} - C:\Program Files\Microsoft\Search Enhancement Pack\Search Helper\SEPsearchhelperie.dll
O2 - BHO: Groove GFS Browser Helper - {72853161-30C5-4D22-B7F9-0BBC1D38A37E} - C:\Program Files\Microsoft Office\Office12\GrooveShellExtensions.dll
O2 - BHO: Guida per l'accesso a Windows Live - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Common Files\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: AVG Security Toolbar BHO - {A3BC75A2-1F87-4686-AA43-5347D756017C} - C:\Program Files\AVG\AVG9\Toolbar\IEToolbar.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Program Files\Java\jre6\bin\jp2ssv.dll
O2 - BHO: Windows Live Toolbar Helper - {E15A8DC0-8516-42A1-81EA-DC94EC1ACF10} - C:\Program Files\Windows Live\Toolbar\wltcore.dll
O2 - BHO: OfferBox - {FC0D62C2-9640-4AEB-A5D5-CF25DF11FA8C} - C:\Program Files\OfferBox\OfferBoxBHO.dll
O3 - Toolbar: &Windows Live Toolbar - {21FA44EF-376D-4D53-9B0F-8A89D3229068} - C:\Program Files\Windows Live\Toolbar\wltcore.dll
O3 - Toolbar: AVG Security Toolbar - {CCC7A320-B3CA-4199-B1A6-9F516DD69829} - C:\Program Files\AVG\AVG9\Toolbar\IEToolbar.dll
O4 - HKLM\..\Run: [Windows Defender] %ProgramFiles%\Windows Defender\MSASCui.exe -hide
O4 - HKLM\..\Run: [SynTPEnh] C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
O4 - HKLM\..\Run: [topi] C:\Program Files\TOSHIBA\Toshiba Online Product Information\topi.exe -startup
O4 - HKLM\..\Run: [IgfxTray] C:\Windows\system32\igfxtray.exe
O4 - HKLM\..\Run: [HotKeysCmds] C:\Windows\system32\hkcmd.exe
O4 - HKLM\..\Run: [Persistence] C:\Windows\system32\igfxpers.exe
O4 - HKLM\..\Run: [TPwrMain] %ProgramFiles%\TOSHIBA\Power Saver\TPwrMain.EXE
O4 - HKLM\..\Run: [SmoothView] %ProgramFiles%\Toshiba\SmoothView\SmoothView.exe
O4 - HKLM\..\Run: [00TCrdMain] %ProgramFiles%\TOSHIBA\FlashCards\TCrdMain.exe
O4 - HKLM\..\Run: [Camera Assistant Software] "C:\Program Files\Camera Assistant Software for Toshiba\traybar.exe" /start
O4 - HKLM\..\Run: [GrooveMonitor] "C:\Program Files\Microsoft Office\Office12\GrooveMonitor.exe"
O4 - HKLM\..\Run: [AppleSyncNotifier] C:\Program Files\Common Files\Apple\Mobile Device Support\bin\AppleSyncNotifier.exe
O4 - HKLM\..\Run: [AVG9_TRAY] C:\PROGRA~1\AVG\AVG9\avgtray.exe
O4 - HKCU\..\Run: [Sidebar] C:\Program Files\Windows Sidebar\sidebar.exe /autoRun
O4 - HKCU\..\Run: [TOSCDSPD] C:\Program Files\TOSHIBA\TOSCDSPD\TOSCDSPD.exe
O4 - HKCU\..\Run: [SpybotSD TeaTimer] C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
O4 - HKCU\..\Run: [I&F Viewer toolbar] "C:\Program Files\Photo Toolkit\ivbar\phototoolkitmem.exe" -start
O4 - HKCU\..\Run: [PC Suite Tray] "C:\Program Files\Nokia\Nokia PC Suite 7\PCSuite.exe" -onlytray
O4 - HKCU\..\Run: [msnmsgr] "C:\Program Files\Windows Live\Messenger\msnmsgr.exe" /background
O4 - HKUS\S-1-5-18\..\Run: [kell] c:\program Files\Manson\liser.exe (User 'SYSTEM')
O4 - HKUS\S-1-5-18\..\Run: [TOSHIBA Online Product Information] C:\Program Files\TOSHIBA\Toshiba Online Product Information\topi.exe (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [kell] c:\program Files\Manson\liser.exe (User 'Default user')
O4 - .DEFAULT User Startup: TRDCReminder.lnk = C:\Program Files\TOSHIBA\TRDCReminder\TRDCReminder.exe (User 'Default user')
O8 - Extra context menu item: Add to Google Photos Screensa&ver - res://C:\Windows\system32\GPhotos.scr/200
O8 - Extra context menu item: E&sporta in Microsoft Excel - res://C:\PROGRA~1\MICROS~1\Office12\EXCEL.EXE/3000
O9 - Extra button: Inserisci blog - {219C3416-8CB2-491a-A3C7-D9FCDDC9D600} - C:\Program Files\Windows Live\Writer\WriterBrowserExtension.dll
O9 - Extra 'Tools' menuitem: Inserisci &blog in Windows Live Writer - {219C3416-8CB2-491a-A3C7-D9FCDDC9D600} - C:\Program Files\Windows Live\Writer\WriterBrowserExtension.dll
O9 - Extra button: Invia a OneNote - {2670000A-7350-4f3c-8081-5663EE0C6C49} - C:\PROGRA~1\MICROS~1\Office12\ONBttnIE.dll
O9 - Extra 'Tools' menuitem: I&nvia a OneNote - {2670000A-7350-4f3c-8081-5663EE0C6C49} - C:\PROGRA~1\MICROS~1\Office12\ONBttnIE.dll
O9 - Extra button: Inizia a fare affari su eBay.it! - {76577871-04EC-495E-A12B-91F7C3600AFA} - http://rover.ebay.com/rover/1/724-44559-9400-3/4 (file missing)
O9 - Extra button: Amazon.co.uk - {8A918C1D-E123-4E36-B562-5C1519E434CE} - http://www.amazon.co.uk/exec/obidos/redirect-home?tag=Toshibaukbholink-21&site=home (file missing)
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~1\Office12\REFIEBAR.DLL
O9 - Extra button: (no name) - {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O9 - Extra 'Tools' menuitem: Spybot - Search & Destroy Configuration - {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O16 - DPF: {0CCA191D-13A6-4E29-B746-314DEE697D83} (Facebook Photo Uploader 5 Control) - http://upload.facebook.com/controls/2008.10.10_v5.5.8/FacebookPhotoUploader5.cab
O18 - Protocol: grooveLocalGWS - {88FED34C-F0CA-4636-A375-3CB6248B04CD} - C:\Program Files\Microsoft Office\Office12\GrooveSystemServices.dll
O18 - Protocol: linkscanner - {F274614C-63F8-47D5-A4D1-FBDDE494F8D1} - C:\Program Files\AVG\AVG9\avgpp.dll
O20 - AppInit_DLLs: C:\PROGRA~1\Google\GOOGLE~2\GOEC62~1.DLL,c:\progra~1\Manson\liser.dll,avgrsstx.dll
O22 - SharedTaskScheduler: Component Categories cache daemon - {8C7461EF-2B13-11d2-BE35-3078302C2030} - C:\Windows\system32\browseui.dll
O23 - Service: Agere Modem Call Progress Audio (AgereModemAudio) - Agere Systems - C:\Windows\system32\agrsmsvc.exe
O23 - Service: Apple Mobile Device - Apple Inc. - C:\Program Files\Common Files\Apple\Mobile Device Support\bin\AppleMobileDeviceService.exe
O23 - Service: AVG Free WatchDog (avg9wd) - AVG Technologies CZ, s.r.o. - C:\Program Files\AVG\AVG9\avgwdsvc.exe
O23 - Service: Bonjour Service - Apple Inc. - C:\Program Files\Bonjour\mDNSResponder.exe
O23 - Service: ConfigFree Service - TOSHIBA CORPORATION - C:\Program Files\TOSHIBA\ConfigFree\CFSvcs.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: Servizio iPod (iPod Service) - Apple Inc. - C:\Program Files\iPod\bin\iPodService.exe
O23 - Service: Nero BackItUp Scheduler 3 - Nero AG - C:\Program Files\Nero\Nero8\Nero BackItUp\NBService.exe
O23 - Service: NMIndexingService - Nero AG - C:\Program Files\Common Files\Nero\Lib\NMIndexingService.exe
O23 - Service: SBSD Security Center Service (SBSDWSCService) - Safer Networking Ltd. - C:\Program Files\Spybot - Search & Destroy\SDWinSec.exe
O23 - Service: ServiceLayer - Nokia. - C:\Program Files\PC Connectivity Solution\ServiceLayer.exe
O23 - Service: SmartFaceVWatchSrv - Toshiba - C:\Program Files\TOSHIBA\SmartFaceV\SmartFaceVWatchSrv.exe
O23 - Service: Notebook Performance Tuning Service (TEMPRO) (TemproMonitoringService) - Toshiba Europe GmbH - C:\Program Files\Toshiba TEMPRO\TemproSvc.exe
O23 - Service: TOSHIBA Navi Support Service (TNaviSrv) - TOSHIBA Corporation - C:\Program Files\TOSHIBA\TOSHIBA DVD PLAYER\TNaviSrv.exe
O23 - Service: TOSHIBA Optical Disc Drive Service (TODDSrv) - TOSHIBA Corporation - C:\Windows\system32\TODDSrv.exe
O23 - Service: TOSHIBA Power Saver (TosCoSrv) - TOSHIBA Corporation - C:\Program Files\TOSHIBA\Power Saver\TosCoSrv.exe
O23 - Service: TOSHIBA SMART Log Service - TOSHIBA Corporation - C:\Program Files\TOSHIBA\SMARTLogService\TosIPCSrv.exe
O23 - Service: @%SystemRoot%\System32\TuneUpDefragService.exe,-1 (TuneUp.Defrag) - TuneUp Software - C:\Windows\System32\TuneUpDefragService.exe
O23 - Service: @%SystemRoot%\System32\TUProgSt.exe,-1 (TuneUp.ProgramStatisticsSvc) - TuneUp Software - C:\Windows\System32\TUProgSt.exe

--
End of file - 10747 bytes

Io non sono un grande esperto in fatto di virus,ma il log sembra che non abbia particolari problemi.
Esegui queste operazioni di routine:Disattiva il ripristino di sistema,scarica da aiutamici Malwarebytes,installalo ed aggiornalo,fai una scansione completa del computer ed elimina quello che trova.
Fai una scansione completa con l'antivirus e con Spyboot(aggiornalo prima della scansione e immunizza),infine dai una ripulita con Ccleaner.
Se dopo aver fatto queste operazioni le finestre pubblicitarie non appaiono più riattiva il ripristino di sistema e crea un nuovo punto.
Ho notato che hai attivo il Tea Timer di Spyboot,disattivalo in questo modo:
Clicca su Modalità,seleziona Modalità Avanzate,conferma con Si quindi clicca su Utilità,cerca la voce Resident e clicca,sulla destra nella schermata togliere la spunta a Attiva il modulo Tea Timer.
Come giustamente dice sabbb qui sotto installa il service pack2.

Ti consiglio di installare il Service Pack 2 per Vista, molto importante, poi ci sono 2 file secondo me pericolosi,
si tratta di Manson\liser.exe - Liser.exe è un Trojan / Backdoor. Attendi conferma da Alfonso.

Per info su questo malware: Liser.exe.
Sembra comunque che Malwarebytes' AntiMalware possa essere in grado (se aggiornato a puntino) di rimuoverlo.
Condivido anche il suggerimento di Wolf riguardante il Tea Timer di Spybot, nonché l'idea di installare il SP2 per Vista (installazione da farsi dopo che aver risolto gli altri problemi, ovviamente).

PS: Ben ritrovato, Shapiro!