Ciao! Il problema si è ripresentato (l'unico "evento" di rilievo precedente alla ricomparsa è stato l'aggiornamento all'ultima versione di Firefox).
Non avendo -come al solito- risolto con antivirus e antispyware, vi chiederei di guardare il mio log di HiJackThis. Ma ci sarà un modo di eliminare per sempre il problema? Grazie in anticipo!

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 16.24.36, on 19/09/2007
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP2 (6.00.2900.2180)
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\ZoneLabs\vsmon.exe
C:\WINDOWS\Explorer.EXE
C:\Programmi\File comuni\Symantec Shared\ccSetMgr.exe
C:\Programmi\File comuni\Symantec Shared\ccEvtMgr.exe
C:\WINDOWS\system32\LEXBCES.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\system32\LEXPPS.EXE
C:\Programmi\Grisoft\AVG Anti-Spyware 7.5\guard.exe
C:\Programmi\Symantec AntiVirus\DefWatch.exe
C:\Programmi\File comuni\Microsoft Shared\VS7DEBUG\MDM.EXE
C:\WINDOWS\system32\IoctlSvc.exe
C:\WINDOWS\system32\svchost.exe
C:\Programmi\Symantec AntiVirus\Rtvscan.exe
C:\WINDOWS\system32\igfxtray.exe
C:\WINDOWS\system32\hkcmd.exe
C:\Programmi\Synaptics\SynTP\SynTPLpr.exe
C:\Programmi\Synaptics\SynTP\SynTPEnh.exe
C:\SYSINFO\CyberLink\PowerDVD\PDVDServ.exe
C:\Programmi\Acer\Notebook Manager\almxptray.exe
C:\Programmi\Launch Manager\LaunchAp.exe
C:\Programmi\Launch Manager\PowerKey.exe
C:\Programmi\Launch Manager\HotkeyApp.exe
C:\Programmi\Launch Manager\OSDCtrl.exe
C:\Programmi\Launch Manager\CtrlVol.exe
C:\Programmi\Launch Manager\Wbutton.exe
C:\WINDOWS\AGRSMMSG.exe
C:\WINDOWS\SOUNDMAN.EXE
C:\Programmi\A-DATA\USB Flash Disk Utility\PLBkMon.exe
C:\Programmi\Lexmark X1100 Series\lxbkbmgr.exe
C:\Programmi\Java\jre1.6.0_01\bin\jusched.exe
C:\Programmi\Lexmark X1100 Series\lxbkbmon.exe
C:\Programmi\File comuni\Symantec Shared\ccApp.exe
C:\PROGRA~1\SYMANT~1\VPTray.exe
C:\Programmi\Grisoft\AVG Anti-Spyware 7.5\avgas.exe
C:\Programmi\Zone Labs\ZoneAlarm\zlclient.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programmi\Messenger\msmsgs.exe
C:\Programmi\FreePOPs\freepopsd.exe
C:\PROGRA~1\Magentic\bin\MgApp.exe
C:\Programmi\HiJackThis\HiJackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = about:blank
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Collegamenti
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} -

C:\Programmi\Java\jre1.6.0_01\bin\ssv.dll
O4 - HKLM\..\Run: [preload] C:\Windows\RUNXMLPL.exe
O4 - HKLM\..\Run: [IgfxTray] C:\WINDOWS\system32\igfxtray.exe
O4 - HKLM\..\Run: [HotKeysCmds] C:\WINDOWS\system32\hkcmd.exe
O4 - HKLM\..\Run: [SynTPLpr] C:\Programmi\Synaptics\SynTP\SynTPLpr.exe
O4 - HKLM\..\Run: [SynTPEnh] C:\Programmi\Synaptics\SynTP\SynTPEnh.exe
O4 - HKLM\..\Run: [RemoteControl] C:\SYSINFO\CyberLink\PowerDVD\PDVDServ.exe
O4 - HKLM\..\Run: [AcerNotebookManager] C:\Programmi\Acer\Notebook Manager\almxptray.exe
O4 - HKLM\..\Run: [LaunchAp] C:\Programmi\Launch Manager\LaunchAp.exe
O4 - HKLM\..\Run: [PowerKey] "C:\Programmi\Launch Manager\PowerKey.exe"
O4 - HKLM\..\Run: [LManager] C:\Programmi\Launch Manager\HotkeyApp.exe
O4 - HKLM\..\Run: [LMgrOSD] C:\Programmi\Launch Manager\OSDCtrl.exe
O4 - HKLM\..\Run: [CtrlVol] C:\Programmi\Launch Manager\CtrlVol.exe
O4 - HKLM\..\Run: [Wbutton] "C:\Programmi\Launch Manager\Wbutton.exe"
O4 - HKLM\..\Run: [IMJPMIG8.1] "C:\WINDOWS\IME\imjp8_1\IMJPMIG.EXE" /Spoil /RemAdvDef

/Migration32
O4 - HKLM\..\Run: [MSPY2002] C:\WINDOWS\system32\IME\PINTLGNT\ImScInst.exe /SYNC
O4 - HKLM\..\Run: [PHIME2002ASync] C:\WINDOWS\system32\IME\TINTLGNT\TINTSETP.EXE /SYNC
O4 - HKLM\..\Run: [PHIME2002A] C:\WINDOWS\system32\IME\TINTLGNT\TINTSETP.EXE /IMEName
O4 - HKLM\..\Run: [AGRSMMSG] AGRSMMSG.exe
O4 - HKLM\..\Run: [LtMoh] C:\Programmi\ltmoh\Ltmoh.exe
O4 - HKLM\..\Run: [IMEKRMIG6.1] C:\WINDOWS\ime\imkr6_1\IMEKRMIG.EXE
O4 - HKLM\..\Run: [SoundMan] SOUNDMAN.EXE
O4 - HKLM\..\Run: [ADATA_PLUtil] C:\Programmi\A-DATA\USB Flash Disk Utility\PLBkMon.exe
O4 - HKLM\..\Run: [Lexmark X1100 Series] "C:\Programmi\Lexmark X1100 Series\lxbkbmgr.exe"
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Programmi\Java\jre1.6.0_01\bin\jusched.exe "
O4 - HKLM\..\Run: [WinampAgent] C:\Programmi\Winamp\winampa.exe
O4 - HKLM\..\Run: [AAWTray] C:\Programmi\Lavasoft\Ad-Aware 2007\AAWTray.exe
O4 - HKLM\..\Run: [ccApp] "C:\Programmi\File comuni\Symantec Shared\ccApp.exe"
O4 - HKLM\..\Run: [vptray] C:\PROGRA~1\SYMANT~1\VPTray.exe
O4 - HKLM\..\Run: [!AVG Anti-Spyware] "C:\Programmi\Grisoft\AVG Anti-Spyware 7.5\avgas.exe"

/minimized
O4 - HKLM\..\Run: [ZoneAlarm Client] "C:\Programmi\Zone Labs\ZoneAlarm\zlclient.exe"
O4 - HKCU\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [MSMSGS] "C:\Programmi\Messenger\msmsgs.exe" /background
O4 - HKCU\..\Run: [Magentic] C:\PROGRA~1\Magentic\bin\Magentic.exe /c
O4 - HKUS\S-1-5-19\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SERVIZIO

LOCALE')
O4 - HKUS\S-1-5-20\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SERVIZIO DI

RETE')
O4 - HKUS\S-1-5-18\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'Default user')
O4 - Startup: FreePOPs.lnk = C:\Programmi\FreePOPs\freepopsd.exe
O8 - Extra context menu item: E&sporta in Microsoft Excel - res://C:\PROGRA~1\MICROS~2

\OFFICE11\EXCEL.EXE/3000
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} -

C:\Programmi\Java\jre1.6.0_01\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Sun Java Console - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} -

C:\Programmi\Java\jre1.6.0_01\bin\ssv.dll
O9 - Extra button: Ricerche - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2

\OFFICE11\REFIEBAR.DLL
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
O16 - DPF: {6414512B-B978-451D-A0D8-FCFDF33E833C} (WUWebControl Class) -

http://www.update.microsoft.com/wind...uweb_site.cab?

1189777358801
O16 - DPF: {C3F79A2B-B9B4-4A66-B012-3EE46475B072} (MessengerStatsClient Class) -

http://messenger.zone.msn.com/binary...t.cab56907.cab
O20 - Winlogon Notify: winqta32 - C:\WINDOWS\SYSTEM32\winqta32.dll
O23 - Service: AVG Anti-Spyware Guard - GRISOFT s.r.o. - C:\Programmi\Grisoft\AVG Anti-

Spyware 7.5\guard.exe
O23 - Service: Symantec Event Manager (ccEvtMgr) - Symantec Corporation - C:\Programmi\File

comuni\Symantec Shared\ccEvtMgr.exe
O23 - Service: Symantec Password Validation (ccPwdSvc) - Symantec Corporation -

C:\Programmi\File comuni\Symantec Shared\ccPwdSvc.exe
O23 - Service: Symantec Settings Manager (ccSetMgr) - Symantec Corporation -

C:\Programmi\File comuni\Symantec Shared\ccSetMgr.exe
O23 - Service: Symantec AntiVirus Definition Watcher (DefWatch) - Symantec Corporation -

C:\Programmi\Symantec AntiVirus\DefWatch.exe
O23 - Service: LexBce Server (LexBceS) - Lexmark International, Inc. - C:\WINDOWS\system32

\LEXBCES.EXE
O23 - Service: PLFlash DeviceIoControl Service - Prolific Technology Inc. -

C:\WINDOWS\system32\IoctlSvc.exe
O23 - Service: SAVRoam (SavRoam) - symantec - C:\Programmi\Symantec AntiVirus\SavRoam.exe
O23 - Service: Symantec Network Drivers Service (SNDSrvc) - Symantec Corporation -

C:\Programmi\File comuni\Symantec Shared\SNDSrvc.exe
O23 - Service: Symantec SPBBCSvc (SPBBCSvc) - Symantec Corporation - C:\Programmi\File

comuni\Symantec Shared\SPBBC\SPBBCSvc.exe
O23 - Service: Symantec AntiVirus - Symantec Corporation - C:\Programmi\Symantec

AntiVirus\Rtvscan.exe
O23 - Service: TrueVector Internet Monitor (vsmon) - Zone Labs, LLC - C:\WINDOWS\system32

\ZoneLabs\vsmon.exe

--
End of file - 7786 bytes