ecco il log:Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 10.44.54, on 09/01/2010
Platform: Windows XP SP3 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.20815)
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:\Programmi\Avira\AntiVir Desktop\avguard.exe
C:\WINDOWS\System32\svchost.exe
C:\Programmi\Java\jre6\bin\jqs.exe
C:\Programmi\File comuni\Microsoft Shared\VS7Debug\mdm.exe
C:\Programmi\CDBurnerXP\NMSAccessU.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\Programmi\Alcohol Soft\Alcohol 120\StarWind\StarWindServiceAE.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\RUNDLL32.EXE
C:\Programmi\VIAudioi\SBADeck\ADeck.exe
C:\WINDOWS\vsnpstd.exe
C:\wov\WheelsOfVolume\WheelsOfVolume.exe
C:\Programmi\Avira\AntiVir Desktop\avgnt.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programmi\InterVideo\Common\Bin\WinCinemaMgr.exe
C:\Programmi\Mozilla Firefox\firefox.exe
C:\Programmi\Trend Micro\HijackThis\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://google.mini20.com
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
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = local
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Collegamenti
O2 - BHO: AcroIEHelperStub - {18DF081C-E8AD-4283-A596-FA578C2EBDC3} - C:\Programmi\File comuni\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll
O2 - BHO: (no name) - {5C255C8A-E604-49b4-9D64-90988571CECB} - (no file)
O2 - BHO: Guida per l'accesso a Windows Live - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Programmi\File comuni\Microsoft Shared\Windows Live\WindowsLiveLogin.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: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [AudioDeck] C:\Programmi\VIAudioi\SBADeck\ADeck.exe 1
O4 - HKLM\..\Run: [snpstd] C:\WINDOWS\vsnpstd.exe
O4 - HKLM\..\Run: [Adobe Reader Speed Launcher] "C:\Programmi\Adobe\Reader 9.0\Reader\Reader_sl.exe"
O4 - HKLM\..\Run: [Adobe ARM] "C:\Programmi\File comuni\Adobe\ARM\1.0\AdobeARM.exe"
O4 - HKLM\..\Run: [FuzLez WheelsOfVolume] "C:\wov\WheelsOfVolume\WheelsOfVolume.exe"
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [avgnt] "C:\Programmi\Avira\AntiVir Desktop\avgnt.exe" /min
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - HKUS\S-1-5-18\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SYSTEM')
O4 - HKUS\S-1-5-18\..\Run: [MsnMsgr] "C:\Programmi\Windows Live\Messenger\MsnMsgr.Exe" /background (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'Default user')
O4 - Global Startup: InterVideo WinCinema Manager.lnk = C:\Programmi\InterVideo\Common\Bin\WinCinemaMgr.exe
O4 - Global Startup: Microsoft Office.lnk = C:\Programmi\Microsoft Office\Office10\OSA.EXE
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
O16 - DPF: {5D6F45B3-9043-443D-A792-115447494D24} (UnoCtrl Class) - http://messenger.zone.msn.com/MessengerGamesContent/GameContent/it/uno1/GAME_UNO1.cab
O16 - DPF: {C3F79A2B-B9B4-4A66-B012-3EE46475B072} (MessengerStatsClient Class) - http://messenger.zone.msn.com/binary/MessengerStatsPAClient.cab56907.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{A07B1AB4-9D92-4338-A005-1C0815F68C47}: NameServer = 85.37.17.11 85.38.28.69
O20 - Winlogon Notify: !SASWinLogon - C:\Programmi\SUPERAntiSpyware\SASWINLO.dll
O23 - Service: Adobe LM Service - Adobe Systems - C:\Programmi\File comuni\Adobe Systems Shared\Service\Adobelmsvc.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: avast! iAVS4 Control Service (aswUpdSv) - ALWIL Software - C:\Programmi\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: avast! Antivirus - ALWIL Software - C:\Programmi\Alwil Software\Avast4\ashServ.exe
O23 - Service: avast! Mail Scanner - ALWIL Software - C:\Programmi\Alwil Software\Avast4\ashMaiSv.exe
O23 - Service: avast! Web Scanner - ALWIL Software - C:\Programmi\Alwil Software\Avast4\ashWebSv.exe
O23 - Service: Java Quick Starter (JavaQuickStarterService) - Sun Microsystems, Inc. - C:\Programmi\Java\jre6\bin\jqs.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: StarWind AE Service (StarWindServiceAE) - Rocket Division Software - C:\Programmi\Alcohol Soft\Alcohol 120\StarWind\StarWindServiceAE.exe

--
End of file - 5977 bytes

Ciao, Stefano!
Perdonami il rilievo (del tutto amichevole, t'assicuro), ma il tuo post sarebbe certamente più visibile agli esperti (e riceverebbe più celere risposta) se tu l'andassi a postare nella sezione "Virus, sicurezza e privacy"...

nell'attesa di postarlo nella giusta sezione,fixa queste chaivi, seguendo questa guida:
http://www.aiutamici.com/software?ID=11175

O2 - BHO: (no name) - {5C255C8A-E604-49b4-9D64-90988571CECB} - (no file)
O16 - DPF: {5D6F45B3-9043-443D-A792-115447494D24} (UnoCtrl Class) - http://messenger.zone.msn.com/MessengerGamesContent/GameContent/it/uno1/GAME_UNO1.cab
O16 - DPF: {C3F79A2B-B9B4-4A66-B012-3EE46475B072} (MessengerStatsClient Class) - http://messenger.zone.msn.com/binary/MessengerStatsPAClient.cab56907.cab


La cosa sconcertante è che hai 2 ANTIVIRUS, decidi quale tenere....
In pratica non si capisce, AVAST l'hai disinstallato?