Per avviare xp, spesso devo resettare il pc 3/4 volte.
Segue il log.
Grazie

*****************************************************************
Logfile of Trend Micro HijackThis v2.0.4
Scan saved at 17.06.00, on 24/03/2014
Platform: Windows XP SP3 (WinNT 5.01.2600)
MSIE: Internet Explorer v8.00 (8.00.6001.18702)
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\Ati2evxx.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Programmi\Avira\AntiVir Desktop\sched.exe
C:\WINDOWS\system32\Ati2evxx.exe
C:\WINDOWS\Explorer.EXE
C:\Programmi\File comuni\ArcSoft\Connection Service\Bin\ACService.exe
C:\Programmi\Avira\AntiVir Desktop\avguard.exe
C:\Programmi\AskPartnerNetwork\Toolbar\apnmcp.exe
C:\Programmi\ASUS\AXSP\1.00.13\atkexComSvc.exe
C:\Programmi\ASUS\AAHM\1.00.12\aaHMSvc.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\Programmi\File comuni\MAGIX Services\Database\bin\FABS.exe
C:\Programmi\Java\jre7\bin\jqs.exe
C:\WINDOWS\system32\LEXBCES.EXE
C:\WINDOWS\system32\LEXPPS.EXE
C:\WINDOWS\system32\lxczcoms.exe
c:\Programmi\File comuni\Protexis\License Service\PsiService_2.exe
D:\Programmi\Diskutility\Macrium\Reflect\ReflectService.exe
C:\WINDOWS\system32\tcpsvcs.exe
C:\Programmi\Analog Devices\SoundMAX\SMAgent.exe
C:\Programmi\Spyware Terminator\st_rsser.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\StkASv2K.exe
C:\Programmi\File comuni\Ulead Systems\DVD\ULCDRSvr.exe
C:\WINDOWS\system32\SearchIndexer.exe
C:\Programmi\Zune\ZuneBusEnum.exe
C:\Programmi\Avira\AntiVir Desktop\avgnt.exe
C:\Programmi\ATI Multimedia\main\launchpd.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programmi\Avira\AntiVir Desktop\avshadow.exe
C:\Programmi\Avira\AntiVir Desktop\AVWEBGRD.EXE
D:\Programmi\Diskutility\totalcmd\TOTALCMD.EXE
C:\Programmi\Mozilla Firefox\firefox.exe
C:\Programmi\Trend Micro\HijackThis\HijackThis.exe
D:\Programmi\Microsoft Office\Office12\EXCEL.EXE
C:\Programmi\Google\Update\GoogleUpdate.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.mps.it/index.htm
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://go.microsoft.com/fwlink/?LinkId=69157
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://go.microsoft.com/fwlink/?LinkId=69157
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant =
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Local Page =
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Local Page =
R1 - HKCU\Software\Microsoft\Internet Connection Wizard,ShellNext = http://r.office.microsoft.com/r/rlidOfficeSearchInstallRTM?clid=1040&ver=12&app=outlook.exe&p1=32&p2=5&p3=1
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Collegamenti
F2 - REG:system.ini: UserInit=C:\WINDOWS\system32\userinit.exe
O2 - BHO: AcroIEHelperStub - {18DF081C-E8AD-4283-A596-FA578C2EBDC3} - C:\Programmi\File comuni\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll
O2 - BHO: Avira SearchFree Toolbar BHO - {41564952-412D-5637-4300-7A786E7484D7} - "C:\Programmi\AskPartnerNetwork\Toolbar\AVIRA-V7C\Passport.dll" (file missing)
O2 - BHO: Wondershare Player 1.6.0 - {43D9786F-A485-683B-9B5B-ACC97ABC17FC} - (no file)
O2 - BHO: Java(tm) Plug-In SSV Helper - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Programmi\Java\jre7\bin\ssv.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - C:\Programmi\Google\Google Toolbar\GoogleToolbar_32.dll
O2 - BHO: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Programmi\Google\GoogleToolbarNotifier\5.7.9012.1008\swg.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Programmi\Java\jre7\bin\jp2ssv.dll
O3 - Toolbar: Avira SearchFree Toolbar - {41564952-412D-5637-4300-7A786E7484D7} - "C:\Programmi\AskPartnerNetwork\Toolbar\AVIRA-V7C\Passport.dll" (file missing)
O3 - Toolbar: Google Toolbar - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - C:\Programmi\Google\Google Toolbar\GoogleToolbar_32.dll
O4 - HKLM\..\Run: [avgnt] "C:\Programmi\Avira\AntiVir Desktop\avgnt.exe" /min
O4 - HKCU\..\Run: [ATI Launchpad] "C:\Programmi\ATI Multimedia\main\launchpd.exe"
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O6 - HKLM\Software\Policies\Microsoft\Internet Explorer\Restrictions present
O9 - Extra button: Invia a OneNote - {2670000A-7350-4f3c-8081-5663EE0C6C49} - D:\PROGRA~1\MICROS~1\Office12\ONBttnIE.dll
O9 - Extra 'Tools' menuitem: I&nvia a OneNote - {2670000A-7350-4f3c-8081-5663EE0C6C49} - D:\PROGRA~1\MICROS~1\Office12\ONBttnIE.dll
O9 - Extra button: Shareiiit options - {38771E1F-85E0-4A3E-92D8-1D7E62C32719} - C:\WINDOWS\system32\shdocvw.dll
O9 - Extra button: ATI TV - {44226DFF-747E-4edc-B30C-78752E50CD0C} - C:\Programmi\ATI Multimedia\dtv\EXPLBAR.DLL
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - D:\PROGRA~1\MICROS~1\Office12\REFIEBAR.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:\WINDOWS\system32\shdocvw.dll
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\WINDOWS\system32\shdocvw.dll
O17 - HKLM\System\CCS\Services\Tcpip\..\{0BA66152-A1CC-4104-9874-570B63BEEA3F}: NameServer = 85.37.17.5 85.38.28.77
O17 - HKLM\System\CS2\Services\Tcpip\..\{0BA66152-A1CC-4104-9874-570B63BEEA3F}: NameServer = 85.37.17.5 85.38.28.77
O17 - HKLM\System\CS3\Services\Tcpip\..\{0BA66152-A1CC-4104-9874-570B63BEEA3F}: NameServer = 85.37.17.5 85.38.28.77
O18 - Protocol: grooveLocalGWS - {88FED34C-F0CA-4636-A375-3CB6248B04CD} - D:\Programmi\Microsoft Office\Office12\GrooveSystemServices.dll
O18 - Protocol: skype4com - {FFC8B962-9B40-4DFF-9458-1830C7DD7F5D} - C:\PROGRA~1\FILECO~1\Skype\SKYPE4~1.DLL
O18 - Protocol: WSIEChrome - {6D02ED5F-FD0D-4C4C - (no file)
O22 - SharedTaskScheduler: Precaricatore Browseui - {438755C2-A8BA-11D1-B96B-00A0C90312E1} - C:\WINDOWS\system32\browseui.dll
O22 - SharedTaskScheduler: Daemon di cache delle categorie di componenti - {8C7461EF-2B13-11d2-BE35-3078302C2030} - C:\WINDOWS\system32\browseui.dll
O23 - Service: ArcSoft Connect Daemon (ACDaemon) - ArcSoft Inc. - C:\Programmi\File comuni\ArcSoft\Connection Service\Bin\ACService.exe
O23 - Service: Adobe Flash Player Update Service (AdobeFlashPlayerUpdateSvc) - Adobe Systems Incorporated - C:\WINDOWS\system32\Macromed\Flash\FlashPlayerUpdateService.exe
O23 - Service: Avira Pianificatore (AntiVirSchedulerService) - Avira Operations GmbH & Co. KG - C:\Programmi\Avira\AntiVir Desktop\sched.exe
O23 - Service: Avira Real-Time Protection (AntiVirService) - Avira Operations GmbH & Co. KG - C:\Programmi\Avira\AntiVir Desktop\avguard.exe
O23 - Service: Avira Web Protection (AntiVirWebService) - Avira Operations GmbH & Co. KG - C:\Programmi\Avira\AntiVir Desktop\AVWEBGRD.EXE
O23 - Service: Servizio di aggiornamento Ask (APNMCP) - APN LLC. - C:\Programmi\AskPartnerNetwork\Toolbar\apnmcp.exe
O23 - Service: ASUS Com Service (asComSvc) - Unknown owner - C:\Programmi\ASUS\AXSP\1.00.13\atkexComSvc.exe
O23 - Service: ASUS HM Com Service (asHmComSvc) - Unknown owner - C:\Programmi\ASUS\AAHM\1.00.12\aaHMSvc.exe
O23 - Service: Ati HotKey Poller - ATI Technologies Inc. - C:\WINDOWS\system32\Ati2evxx.exe
O23 - Service: ATI Smart - Unknown owner - C:\WINDOWS\system32\ati2sgag.exe
O23 - Service: FABS - Helping agent for MAGIX media database (Fabs) - MAGIX AG - C:\Programmi\File comuni\MAGIX Services\Database\bin\FABS.exe
O23 - Service: Firebird Server - MAGIX Instance (FirebirdServerMAGIXInstance) - MAGIX® - C:\Programmi\File comuni\MAGIX Services\Database\bin\fbserver.exe
O23 - Service: Servizio di Google Update (gupdate) (gupdate) - Google Inc. - C:\Programmi\Google\Update\GoogleUpdate.exe
O23 - Service: Servizio Google Update (gupdatem) (gupdatem) - Google Inc. - C:\Programmi\Google\Update\GoogleUpdate.exe
O23 - Service: Google Software Updater (gusvc) - Google - C:\Programmi\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: Java Quick Starter (JavaQuickStarterService) - Oracle Corporation - C:\Programmi\Java\jre7\bin\jqs.exe
O23 - Service: LexBce Server (LexBceS) - Lexmark International, Inc. - C:\WINDOWS\system32\LEXBCES.EXE
O23 - Service: lxcz_device - - C:\WINDOWS\system32\lxczcoms.exe
O23 - Service: Mozilla Maintenance Service (MozillaMaintenance) - Mozilla Foundation - C:\Programmi\Mozilla Maintenance Service\maintenanceservice.exe
O23 - Service: Protexis Licensing V2 (PSI_SVC_2) - Protexis Inc. - c:\Programmi\File comuni\Protexis\License Service\PsiService_2.exe
O23 - Service: Macrium Reflect Image Mounting Service (ReflectService) - Unknown owner - D:\Programmi\Diskutility\Macrium\Reflect\ReflectService.exe
O23 - Service: Skype Updater (SkypeUpdate) - Skype Technologies - C:\Programmi\Skype\Updater\Updater.exe
O23 - Service: SoundMAX Agent Service (SoundMAX Agent Service (default)) - Analog Devices, Inc. - C:\Programmi\Analog Devices\SoundMAX\SMAgent.exe
O23 - Service: Spyware Terminator 2012 Realtime Shield Service (ST2012_Svc) - Crawler.com - C:\Programmi\Spyware Terminator\st_rsser.exe
O23 - Service: Syntek STK1160 Service (StkASSrv) - Syntek America Inc. - C:\WINDOWS\System32\StkASv2K.exe
O23 - Service: Ulead Burning Helper (UleadBurningHelper) - Ulead Systems, Inc. - C:\Programmi\File comuni\Ulead Systems\DVD\ULCDRSvr.exe

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End of file - 9816 bytes

Fai le seguenti scansioni:

Scarica ed installa MalwareBytes:
clicca qui per il download : http://www.aiutamici.com/software?id=80346
Clicca su: Link al sito principale, poi nella pagina che appare clicca su: Free Version Download.
Prima di fare la scansione AGGIORNALO. (è molto importante)
Esegui una scansione COMPLETA del sistema. (NON veloce)
Elimina gli eventuali file infetti trovati. (li devi selezionare, e poi cliccare su "Rimuovi selezionati")
Posta il log.

Scarica Adwcleaner sul desktop:
http://general-changelog-team.fr/fr/downloads/finish/20-outils-de-xplode/2-adwcleaner
Chiudi tutti i browser (è importante IE,Firefox Chrome ecc...)
Clicca sul pulsante "Scan".
Finita la scansione clicca su "Clean"
Conferma con OK le varie finestre che ti compariranno.
Il pc si riavvierà, e uscirà il log con le eliminazioni.
Postalo qui.

Scarica JunkerRemovalTool da qui: http://thisisudax.org/downloads/JRT.exe
Una volta scaricato chiudere tutti i programmi e il browser, per evitare conflitti disattiva momentaneamente anche l’antivirus, lancialo cliccando sull’eseguibile.
Per Vista win 7 e win 8 clic col destro sull’eseguibile ed Eseguire come Amministratore.
Appare il prompt dei comandi, premere un tasto per continuare e il programma inizia la scansione, può durare diversi minuti, lascia fare senza toccare nulla anche se sembra fermo, alla fine appare il Blocco Note col log, JRT.txt copialo e postalo qui.

Tutte le scansioni vanno fatte in modalità NORMALE.

Poi fai una pulizia con Ccleaner compreso il Registro, per il Registro spunta tutte le voci, acconsenti al backup quando richiesto, sempre in Ccleaner vai in Strumenti Ripristino Sistema seleziona tutte le voci tranne l'ultima che non è selezionabile e rimane per sicurezza, poi clic su Rimuovi.
Se non conosci il programma, lo trovi su Aiutamici sezione software.

Vai in C:\windows, cerca la cartella Prefetch aprila ed elimina tutto il contenuto, non eliminare la cartella.

Dimmi se il pc è migliorato. Ciao