Ciao,
ho inavvertitamente avviato un file mascherato
da MP3 che invece conteneva il virus " EXP/ASF.GetCodec.Gen ".
Per dirla tutta quando Windows Media Player ha cercato di eseguirlo
mi ha chiesto se volevo eseguirlo comunque visto che non lo riconosceva
ed io gli ho detto di Annullare. Al momento mi è andato un po' in palla
ma mi pare che Antivir che rileva regolarmente questo virus mi abbia
comunque eliminato il file.
Siccome però mi sono un po' spaventato ho rieseguito il controllo del pc e sembra ok.
Riporto qui di seguito anche il log se me lo controllate sono più sicuro, grazie

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 20.53.16, on 29/06/2009
Platform: Windows XP SP3 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16850)
Boot mode: Normal

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Programmi\Avira\AntiVir Desktop\sched.exe
C:\Acer\eManager\anbmServ.exe
C:\Programmi\Avira\AntiVir Desktop\avguard.exe
C:\Programmi\Java\jre6\bin\jqs.exe
C:\Programmi\Maxtor\Sync\SyncServices.exe
C:\Programmi\CDBurnerXP\NMSAccessU.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\Programmi\PC Tools Firewall Plus\FWService.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\Explorer.EXE
C:\Programmi\Synaptics\SynTP\SynTPLpr.exe
C:\Programmi\Synaptics\SynTP\SynTPEnh.exe
C:\Program Files\Launch Manager\LaunchAp.exe
C:\Program Files\Launch Manager\PowerKey.exe
C:\Program Files\Launch Manager\HotkeyApp.exe
C:\Program Files\Launch Manager\CtrlVol.exe
C:\Program Files\Launch Manager\OSDCtrl.exe
C:\Program Files\Launch Manager\Wbutton.exe
C:\WINDOWS\system32\VTTimer.exe
C:\WINDOWS\AGRSMMSG.exe
C:\Program Files\Arcade\PCMService.exe
C:\Programmi\ltmoh\Ltmoh.exe
C:\WINDOWS\CameraFixer.exe
C:\Programmi\Java\jre6\bin\jusched.exe
C:\Programmi\Avira\AntiVir Desktop\avgnt.exe
C:\Programmi\PC Tools Firewall Plus\FirewallGUI.exe
C:\WINDOWS\tsnpstd3.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programmi\Microsoft ActiveSync\wcescomm.exe
C:\WINDOWS\system32\wbem\wmiapsrv.exe
C:\PROGRA~1\MICROS~4\rapimgr.exe
C:\Programmi\Trend Micro\HijackThis\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://aziende.pubblicitaonline.it/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://go.microsoft.com/fwlink/?LinkId=69157
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\Main,Start Page = http://go.microsoft.com/fwlink/?LinkId=69157
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Local Page =
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Local Page =
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Collegamenti
R3 - URLSearchHook: Yahoo! Toolbar con blocco Pop-Up - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - (no file)
O2 - BHO: Spybot-S&D IE Protection - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Programmi\Java\jre6\bin\jp2ssv.dll
O2 - BHO: JQSIEStartDetectorImpl - {E7E6F031-17CE-4C07-BC86-EABFE594F69C} - C:\Programmi\Java\jre6\lib\deploy\jqs\ie\jqs_plugin.dll
O4 - HKLM\..\Run: [preload] C:\Windows\RUNXMLPL.exe
O4 - HKLM\..\Run: [SynTPLpr] C:\Programmi\Synaptics\SynTP\SynTPLpr.exe
O4 - HKLM\..\Run: [SynTPEnh] C:\Programmi\Synaptics\SynTP\SynTPEnh.exe
O4 - HKLM\..\Run: [LaunchAp] C:\Program Files\Launch Manager\LaunchAp.exe
O4 - HKLM\..\Run: [PowerKey] "C:\Program Files\Launch Manager\PowerKey.exe"
O4 - HKLM\..\Run: [LManager] C:\Program Files\Launch Manager\HotkeyApp.exe
O4 - HKLM\..\Run: [CtrlVol] C:\Program Files\Launch Manager\CtrlVol.exe
O4 - HKLM\..\Run: [LMgrOSD] C:\Program Files\Launch Manager\OSDCtrl.exe
O4 - HKLM\..\Run: [Wbutton] "C:\Program Files\Launch Manager\Wbutton.exe"
O4 - HKLM\..\Run: [VTTrayp] VTtrayp.exe
O4 - HKLM\..\Run: [VTTimer] VTTimer.exe
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [AGRSMMSG] AGRSMMSG.exe
O4 - HKLM\..\Run: [PCMService] "C:\Program Files\Arcade\PCMService.exe"
O4 - HKLM\..\Run: [LtMoh] C:\Programmi\ltmoh\Ltmoh.exe
O4 - HKLM\..\Run: [CameraFixer] C:\WINDOWS\CameraFixer.exe
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Programmi\Java\jre6\bin\jusched.exe"
O4 - HKLM\..\Run: [avgnt] "C:\Programmi\Avira\AntiVir Desktop\avgnt.exe" /min
O4 - HKLM\..\Run: [00PCTFW] "C:\Programmi\PC Tools Firewall Plus\FirewallGUI.exe" -s
O4 - HKLM\..\Run: [tsnpstd3] C:\WINDOWS\tsnpstd3.exe
O4 - HKCU\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [H/PC Connection Agent] "C:\Programmi\Microsoft ActiveSync\wcescomm.exe"
O4 - HKUS\S-1-5-18\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SYSTEM')
O4 - HKUS\S-1-5-18\..\Run: [DWQueuedReporting] "c:\PROGRA~1\FILECO~1\MICROS~1\DW\dwtrig20.exe" -t (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'Default user')
O9 - Extra button: Create Mobile Favorite - {2EAF5BB1-070F-11D3-9307-00C04FAE2D4F} - C:\PROGRA~1\MICROS~4\INetRepl.dll
O9 - Extra button: (no name) - {2EAF5BB2-070F-11D3-9307-00C04FAE2D4F} - C:\PROGRA~1\MICROS~4\INetRepl.dll
O9 - Extra 'Tools' menuitem: Crea preferito portatile... - {2EAF5BB2-070F-11D3-9307-00C04FAE2D4F} - C:\PROGRA~1\MICROS~4\INetRepl.dll
O9 - Extra button: Organizzatore ricerche - {9455301C-CF6B-11D3-A266-00C04F689C50} - C:\Programmi\File comuni\Microsoft Shared\Encarta Researcher\EROPROJ.DLL
O9 - Extra button: (no name) - {B205A35E-1FC4-4CE3-818B-899DBBB3388C} - C:\Programmi\File comuni\Microsoft Shared\Encarta Search Bar\ENCSBAR.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
O9 - Extra button: (no name) - {e2e2dd38-d088-4134-82b7-f2ba38496583} - C:\WINDOWS\Network Diagnostic\xpnetdiag.exe
O9 - Extra 'Tools' menuitem: @xpsp3res.dll,-20001 - {e2e2dd38-d088-4134-82b7-f2ba38496583} - C:\WINDOWS\Network Diagnostic\xpnetdiag.exe
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Programmi\Messenger\msmsgs.exe
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Programmi\Messenger\msmsgs.exe
O23 - Service: Notebook Manager Service (anbmService) - OSA Technologies Inc. - C:\Acer\eManager\anbmServ.exe
O23 - Service: Avira AntiVir Scheduler (AntiVirScheduler) - Avira GmbH - C:\Programmi\Avira\AntiVir Desktop\sched.exe
O23 - Service: Avira AntiVir Guard (AntiVirService) - Avira GmbH - C:\Programmi\Avira\AntiVir Desktop\avguard.exe
O23 - Service: Java Quick Starter (JavaQuickStarterService) - Sun Microsystems, Inc. - C:\Programmi\Java\jre6\bin\jqs.exe
O23 - Service: Maxtor Service (Maxtor Sync Service) - Seagate Technology LLC - C:\Programmi\Maxtor\Sync\SyncServices.exe
O23 - Service: NMSAccessU - Unknown owner - C:\Programmi\CDBurnerXP\NMSAccessU.exe
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe
O23 - Service: PC Tools Firewall Plus (PCToolsFirewallPlus) - PC Tools - C:\Programmi\PC Tools Firewall Plus\FWService.exe
O23 - Service: TuneUp Drive Defrag Service (TuneUp.Defrag) - TuneUp Software GmbH - C:\WINDOWS\System32\TuneUpDefragService.exe

--
End of file - 7290 bytes

Ciao.
Dal log di HJT ti è andata di lusso, visto che non rileva infezioni.
Magari per sicurezza, fai una scansione con Malwarebytes:
Scarica ed installa MalwareBytes:
clicca qui per il download : http://www.aiutamici.com/software?id=80346
Prima di fare la scansione AGGIORNALO. (è molto importante)
Esegui una scansione completa del sistema.
Posta il log. (se non rileva niente, puoi anche non postarlo)
Ciao.