Grazie per l'aiuto Ryan.
Il log che mi hai chiesto è questo:

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 19.04.29, on 20/04/2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16608)
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:\Programmi\Windows Defender\MsMpEng.exe
C:\WINDOWS\System32\svchost.exe
C:\Programmi\Intel\Wireless\Bin\EvtEng.exe
C:\Programmi\Intel\Wireless\Bin\S24EvMon.exe
C:\WINDOWS\system32\spoolsv.exe
c:\programmi\file comuni\logitech\lvmvfm\LVPrcSrv.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\RTHDCPL.EXE
C:\WINDOWS\AGRSMMSG.exe
C:\WINDOWS\system32\RUNDLL32.EXE
C:\Program Files\Acer\Acer Arcade\PCMService.exe
C:\Programmi\Launch Manager\LaunchAp.exe
C:\Programmi\Launch Manager\HotkeyApp.exe
C:\Programmi\Launch Manager\OSDCtrl.exe
C:\Programmi\Launch Manager\Wbutton.exe
C:\Acer\Empowering Technology\eDataSecurity\eDSloader.exe
C:\Acer\Empowering Technology\ePresentation\ePresentation.exe
C:\WINDOWS\system32\LVCOMSX.EXE
C:\Programmi\Acer\OrbiCam\CameraAssistant.exe
C:\WINDOWS\system32\ElkCtrl.exe
C:\Programmi\Java\jre1.6.0_05\bin\jusched.exe
C:\PROGRA~1\Nokia\NOKIAP~1\LAUNCH~1.EXE
C:\Programmi\Macrogaming\SweetIM\SweetIM.exe
C:\Programmi\DAEMON Tools\daemon.exe
C:\Programmi\Windows Defender\MSASCui.exe
C:\Programmi\File comuni\Real\Update_OB\realsched.exe
C:\Programmi\Windows Live\Messenger\MsnMsgr.Exe
C:\Programmi\File comuni\EPSON\EBAPI\eEBSVC.exe
C:\Programmi\G DATA AntiVirus\AVKTray\AVKTray.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programmi\File comuni\Ahead\Lib\NMBgMonitor.exe
C:\Acer\Empowering Technology\Acer.Empowering.Framework.Launcher.exe
C:\Programmi\HTML2POP\html2pop3.exe
C:\Programmi\File comuni\Ahead\Lib\NMIndexStoreSvr.exe
C:\Acer\Empowering Technology\ePerformance\MemCheck.exe
C:\Programmi\G DATA AntiVirus\AVK\AVKService.exe
C:\Programmi\G DATA AntiVirus\AVK\AVKWCtl.exe
C:\Program Files\Acer\Acer Arcade\Kernel\TV\CLCapSvc.exe
C:\Program Files\Acer\Acer Arcade\Kernel\CLML_NTService\CLMLServer.exe
C:\Program Files\Acer\Acer Arcade\Kernel\CLML_NTService\CLMLService.exe
C:\Programmi\File comuni\EPSON\EBAPI\SAgent2.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\Programmi\Intel\Wireless\Bin\RegSrvc.exe
C:\Programmi\CyberLink\Shared Files\RichVideo.exe
C:\WINDOWS\system32\svchost.exe
C:\Programmi\File comuni\G DATA\AVKProxy\AVKProxy.exe
C:\Program Files\Acer\Acer Arcade\Kernel\TV\CLSched.exe
C:\Programmi\File comuni\PCSuite\Services\ServiceLayer.exe
C:\WINDOWS\system32\wscntfy.exe
C:\WINDOWS\system32\wbem\wmiapsrv.exe
C:\WINDOWS\system32\wbem\unsecapp.exe
D:\HiJackThis.exe