Eseguendo una scansione on line con windows live One Care, è stato trovato questo virus : win32/bagle.gen!C, sul file C:\system volume information\_restore....ecc....
Nessun altro antivirus on line me lo ha trovato. Questo è il mio log :
Logfile of HijackThis v1.99.1
Scan saved at 11.32.49, on 30/06/2007
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16473)

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\Alwil Software\Avast4\aswUpdSv.exe
C:\Programmi\Alwil Software\Avast4\ashServ.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:\WINDOWS\eHome\ehRecvr.exe
C:\WINDOWS\eHome\ehSched.exe
C:\WINDOWS\System32\svchost.exe
C:\Programmi\File comuni\Microsoft Shared\VS7DEBUG\MDM.EXE
C:\WINDOWS\System32\PAStiSvc.exe
C:\WINDOWS\system32\svchost.exe
C:\Programmi\Sonic\DigitalMedia LE v7\MyDVD LE\USBDeviceService.exe
C:\PROGRA~1\COMMON~1\X10\Common\x10nets.exe
C:\WINDOWS\Explorer.EXE
C:\Programmi\Alwil Software\Avast4\ashMaiSv.exe
C:\Programmi\Alwil Software\Avast4\ashWebSv.exe
C:\WINDOWS\system32\dllhost.exe
C:\WINDOWS\ehome\ehtray.exe
C:\WINDOWS\sm56hlpr.exe
C:\WINDOWS\eHome\ehmsas.exe
C:\WINDOWS\RTHDCPL.EXE
C:\Programmi\ATI Technologies\ATI.ACE\cli.exe
C:\Programmi\Java\jre1.6.0_01\bin\jusched.exe
C:\Programmi\Sonic\DigitalMedia LE v7\MyDVD LE\DetectorApp.exe
C:\apps\ABoard\ABoard.exe
C:\apps\ABoard\AOSD.exe
C:\WINDOWS\system32\LXSUPMON.EXE
C:\Programmi\Windows Defender\MSASCui.exe
C:\Programmi\Unlocker\UnlockerAssistant.exe
C:\Programmi\Winamp\winampa.exe
C:\Programmi\File comuni\Real\Update_OB\realsched.exe
C:\Programmi\QuickTime\qttask.exe
C:\Programmi\iTunes\iTunesHelper.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\Programmi\iPod\bin\iPodService.exe
C:\Programmi\Grisoft\AVG Anti-Spyware 7.5\avgas.exe
C:\APPS\SMP\SmpSys.exe
C:\Programmi\ATI Technologies\ATI.ACE\cli.exe
C:\Programmi\ATI Technologies\ATI.ACE\cli.exe
C:\Programmi\MSN Messenger\MsnMsgr.Exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programmi\File comuni\Ahead\lib\NMBgMonitor.exe
C:\Programmi\Windows Media Player\WMPNSCFG.exe
C:\WINDOWS\system32\siscmon.exe
C:\Programmi\MSN Messenger\usnsvc.exe
C:\Programmi\Internet Explorer\iexplore.exe
C:\Programmi\File comuni\Microsoft Shared\Windows Live\WLLoginProxy.exe
D:\Documents and Settings\rosa\Documenti\vari setup\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = http://it.rd.yahoo.com/customize/ycomp/defaults/sb/*http://it.docs.yahoo.com/info/ie6.html
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://it.rd.yahoo.com/customize/ycomp/defaults/sp/*http://it.yahoo.com
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.190.it/190/trilogy/jsp/home.do?tabName=HOME+190&BV_UseBVCookie=No&ty_skip_md=true
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 =
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Window Title = Packard Bell
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Collegamenti
O2 - BHO: Yahoo! Toolbar Helper - {02478D38-C3F9-4EFB-9B51-7695ECA05670} - C:\Programmi\Yahoo!\Companion\Installs\cpn\yt.dll
O2 - BHO: Adobe PDF Reader Link Helper - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Programmi\Adobe\Acrobat 7.0\ActiveX\AcroIEHelper.dll
O2 - BHO: (no name) - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Programmi\Java\jre1.6.0_01\bin\ssv.dll
O2 - BHO: Windows Live Sign-in Helper - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Programmi\File comuni\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O3 - Toolbar: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Programmi\Yahoo!\Companion\Installs\cpn\yt.dll
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: [ehTray] C:\WINDOWS\ehome\ehtray.exe
O4 - HKLM\..\Run: [SMSERIAL] sm56hlpr.exe
O4 - HKLM\..\Run: [High Definition Audio Property Page Shortcut] HDAShCut.exe
O4 - HKLM\..\Run: [RTHDCPL] RTHDCPL.EXE
O4 - HKLM\..\Run: [ATICCC] "c:\Programmi\ATI Technologies\ATI.ACE\cli.exe" runtime -Delay
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Programmi\Java\jre1.6.0_01\bin\jusched.exe"
O4 - HKLM\..\Run: [IMJPMIG8.1] "C:\WINDOWS\IME\imjp8_1\IMJPMIG.EXE /Spoil /RemAdvDef /Migration32"
O4 - HKLM\..\Run: [ACTIVBOARD] c:\apps\ABoard\ABoard.exe
O4 - HKLM\..\Run: [PrinTray] C:\WINDOWS\System32\spool\DRIVERS\W32X86\2\printray.exe
O4 - HKLM\..\Run: [LXSUPMON] C:\WINDOWS\system32\LXSUPMON.EXE RUN
O4 - HKLM\..\Run: [Windows Defender] "C:\Programmi\Windows Defender\MSASCui.exe" -hide
O4 - HKLM\..\Run: [UnlockerAssistant] "C:\Programmi\Unlocker\UnlockerAssistant.exe"
O4 - HKLM\..\Run: [WinampAgent] C:\Programmi\Winamp\winampa.exe
O4 - HKLM\..\Run: [TkBellExe] "C:\Programmi\File comuni\Real\Update_OB\realsched.exe" -osboot
O4 - HKLM\..\Run: [QuickTime Task] "C:\Programmi\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [iTunesHelper] "C:\Programmi\iTunes\iTunesHelper.exe"
O4 - HKLM\..\Run: [NeroFilterCheck] C:\WINDOWS\system32\NeroCheck.exe
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [!AVG Anti-Spyware] "C:\Programmi\Grisoft\AVG Anti-Spyware 7.5\avgas.exe" /minimized
O4 - HKCU\..\Run: [SmpcSys] C:\APPS\SMP\SmpSys.exe
O4 - HKCU\..\Run: [MsnMsgr] "C:\Programmi\MSN Messenger\MsnMsgr.Exe" /background
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [updateMgr] C:\Programmi\Adobe\Acrobat 7.0\Reader\AdobeUpdateManager.exe AcRdB7_0_9
O4 - HKCU\..\Run: [BgMonitor_{79662E04-7C6C-4d9f-84C7-88D8A56B10AA}] "C:\Programmi\File comuni\Ahead\lib\NMBgMonitor.exe"
O4 - HKCU\..\Run: [WMPNSCFG] C:\Programmi\Windows Media Player\WMPNSCFG.exe
O4 - Global Startup: Avvio veloce di Adobe Reader.lnk = C:\Programmi\Adobe\Acrobat 7.0\Reader\reader_sl.exe
O4 - Global Startup: siscmon.lnk = ?
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
O11 - Options group: [INTERNATIONAL] International*
O14 - IERESET.INF: START_PAGE_URL=file://C:\APPS\IE\offline\it.htm
O16 - DPF: {193C772A-87BE-4B19-A7BB-445B226FE9A1} (ewidoOnlineScan Control) - http://downloads.ewido.net/ewidoOnlineScan.cab
O16 - DPF: {2250C29C-C5E9-4F55-BE4E-01E45A40FCF1} (CMediaMix Object) - http://musicmix.messenger.msn.com/Medialogic.CAB
O16 - DPF: {512FC5A1-7DE1-43F1-BC0C-371622FCB409} (TotalScan Installer Class) - http://www.nanoscan.com/as/v1/cabs/ascstubie.cab
O16 - DPF: {556DDE35-E955-11D0-A707-000000521957} - http://www.xblock.com/download/xclean_micro.exe
O16 - DPF: {5ED80217-570B-4DA9-BF44-BE107C0EC166} (Windows Live Safety Center Base Module) - http://cdn.scan.onecare.live.com/resource/download/scanner/wlscbase8300.cab
O16 - DPF: {7F8C8173-AD80-4807-AA75-5672F22B4582} (ICSScanner Class) - http://download.zonelabs.com/bin/promotions/spywaredetector/ICSScanner371420.cab
O18 - Protocol: livecall - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\MSNMES~1\MSGRAP~1.DLL
O18 - Protocol: msnim - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\MSNMES~1\MSGRAP~1.DLL
O20 - Winlogon Notify: WgaLogon - C:\WINDOWS\SYSTEM32\WgaLogon.dll
O21 - SSODL: WPDShServiceObj - {AAA288BA-9A4C-45B0-95D7-94D524869DB5} - C:\WINDOWS\system32\WPDShServiceObj.dll
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 - Unknown owner - C:\Programmi\Alwil Software\Avast4\ashMaiSv.exe" /service (file missing)
O23 - Service: avast! Web Scanner - Unknown owner - C:\Programmi\Alwil Software\Avast4\ashWebSv.exe" /service (file missing)
O23 - Service: AVG Anti-Spyware Guard - GRISOFT s.r.o. - C:\Programmi\Grisoft\AVG Anti-Spyware 7.5\guard.exe
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Programmi\File comuni\InstallShield\Driver\1150\Intel 32\IDriverT.exe
O23 - Service: Servizio iPod (iPod Service) - Apple Inc. - C:\Programmi\iPod\bin\iPodService.exe
O23 - Service: LexBce Server (LexBceS) - Lexmark International, Inc. - C:\WINDOWS\system32\LEXBCES.EXE
O23 - Service: STI Simulator - Unknown owner - C:\WINDOWS\System32\PAStiSvc.exe
O23 - Service: X10 Device Network Service (x10nets) - X10 - C:\PROGRA~1\COMMON~1\X10\Common\x10nets.exe

grazie mille per il vostro aiuto.

Per eliminare definitivamente il virus di cui dici:
1) disabilita il Ripristino configurazione di sistema;
2) riavvia il computer;
3) riattiva il Ripristino configurazione di sistema;
4) creati un primo "punto di ripristino" cui poter tornare in caso di bisogna...
Tutto qui: il virus, infatti, ti è stato rilevato proprio nella cartella contenente i "punti di ripristino". Disabilitando il Ripristino configurazione di sistema e poi riavviando, vengon cancellati inevitabilmente TUTTI i "punti di ripristino", inclusi quelli contenenti eventualmente virus...

<img src="http://digilander.libero.it/O_N_E/Emo/EmoPicker/30.gif" border=0> ... mi fa molto piacere che tutto sia risolto!