Ciao Mardux, grazie per la perentoria risposta.
Ecco il log di Hijackthis...


Logfile of HijackThis v1.98.2
Scan saved at 11.31.54, on 24/09/2004
Platform: Windows 2000 SP4 (WinNT 5.00.2195)
MSIE: Internet Explorer v6.00 SP1 (6.00.2800.1106)

Running processes:
C:\WINNT\System32\smss.exe
C:\WINNT\system32\winlogon.exe
C:\WINNT\system32\services.exe
C:\WINNT\system32\lsass.exe
C:\WINNT\system32\svchost.exe
C:\WINNT\system32\spoolsv.exe
C:\Programmi\AVPersonal\AVGUARD.EXE
C:\Programmi\AVPersonal\AVWUPSRV.EXE
C:\Programmi\Software Bluetooth\bin\btwdins.exe
C:\Programmi\File comuni\EPSON\EBAPI\SAgent2.exe
C:\WINNT\System32\svchost.exe
C:\WINNT\System32\nvsvc32.exe
C:\WINNT\system32\regsvc.exe
C:\WINNT\system32\MSTask.exe
C:\WINNT\system32\stisvc.exe
C:\WINNT\System32\WBEM\WinMgmt.exe
C:\WINNT\System32\mspmspsv.exe
C:\WINNT\system32\svchost.exe
C:\WINNT\Explorer.EXE
C:\WINNT\system32\rundll32.exe
C:\Programmi\AVPersonal\AVGNT.EXE
C:\Programmi\Software Bluetooth\BTTray.exe
D:\davide\Utility\messenger\TinMessenger.exe
C:\Documents and Settings\Massara Giuseppe\Desktop\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = http://gw.aliceadsl.it/minisearch
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.google.it
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://gw.aliceadsl.it/home
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.google.it
R1 - HKCU\Software\Microsoft\Internet Explorer\Search,(Default) = ,
R1 - HKLM\Software\Microsoft\Internet Explorer\Search,(Default) = ,
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 = Microsoft Internet Explorer fornito da Alice
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Collegamenti
R3 - Default URLSearchHook is missing
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Programmi\Adobe\Acrobat 5.0\Reader\ActiveX\AcroIEHelper.ocx
O2 - BHO: (no name) - {53707962-6F74-2D53-2644-206D7942484F} - C:\Programmi\Spybot - Search & Destroy\SDHelper.dll
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINNT\system32\msdxm.ocx
O4 - HKLM\..\Run: [Synchronization Manager] mobsync.exe /logon
O4 - HKLM\..\Run: [gcasDtServ] gcasDtServ.exe
O4 - HKLM\..\Run: [AdslTaskBar] rundll32.exe stmctrl.dll,TaskBar
O4 - HKLM\..\Run: [AVGCtrl] "C:\Programmi\AVPersonal\AVGNT.EXE" /min
O4 - Global Startup: BTTray.lnk = C:\Programmi\Software Bluetooth\BTTray.exe
O8 - Extra context menu item: Invia a &Bluetooth - C:\Programmi\Software Bluetooth\btsendto_ie_ctx.htm
O9 - Extra button: @btrez.dll,-4015 - {CCA281CA-C863-46ef-9331-5C8D4460577F} - C:\Programmi\Software Bluetooth\btsendto_ie.htm
O9 - Extra 'Tools' menuitem: @btrez.dll,-4017 - {CCA281CA-C863-46ef-9331-5C8D4460577F} - C:\Programmi\Software Bluetooth\btsendto_ie.htm
O9 - Extra button: Alice - {3A7A4453-E958-4DAC-B0FF-04FC0EB3C154} - http://gw.aliceadsl.it/alice (file missing) (HKCU)
O10 - Broken Internet access because of LSP provider 'osmim.dll' missing
O14 - IERESET.INF: START_PAGE_URL=http://gw.aliceadsl.it/home
O16 - DPF: ppctlcab - http://www.pestscan.com/scanner/ppctlcab.cab
O16 - DPF: {2FC9A21E-2069-4E47-8235-36318989DB13} (PPSDKActiveXScanner.MainScreen) - http://69.44.122.156/scanner/axscanner.cab
O16 - DPF: {72E0F892-B9F1-451D-95A3-2E6C1F45C0DD} (Redirect Control) - http://www.lacasadialice.it/video/cab/Redirect.cab
O16 - DPF: {C2FCEF52-ACE9-11D3-BEBD-00105AA9B6AE} (Symantec RuFSI Registry Information Class) - http://security.symantec.com/sscv6/S.../bin/cabsa.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{076DB69A-C988-433D-A89A-E8E0C4F5BBDF}: NameServer = 217.141.104.205 151.99.125.1
O17 - HKLM\System\CS2\Services\Tcpip\..\{076DB69A-C988-433D-A89A-E8E0C4F5BBDF}: NameServer = 217.141.104.205 151.99.125.1

thank You!