il problema è che c'ho provato a fare quello che mi hai detto ma quando cliccotermina processo mi viene fuori questa scritta: "PROCESSO DI SISTEMA CRITICO. IMPOSSIBILE ELIMINARLO"....
io in ogni caso vi mando il log così date una controllata...

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 12.30.33, on 22/08/2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16705)
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\svchost.exe
C:\Programmi\Alwil Software\Avast4\aswUpdSv.exe
C:\Programmi\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\system32\HPConfig.exe
C:\Programmi\HPQ\Notebook Utilities\HPWirelessMgr.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\wltrysvc.exe
C:\WINDOWS\Explorer.EXE
C:\Programmi\Alwil Software\Avast4\ashMaiSv.exe
C:\WINDOWS\System32\bcmwltry.exe
C:\Programmi\Alwil Software\Avast4\ashWebSv.exe
C:\Programmi\ATI Technologies\ATI Control Panel\atiptaxx.exe
C:\WINDOWS\system32\carpserv.exe
C:\Programmi\File comuni\Real\Update_OB\realsched.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programmi\Nokia\Nokia PC Suite 7\PCSync2.exe
C:\Programmi\PC Connectivity Solution\ServiceLayer.exe
C:\Programmi\PC Connectivity Solution\Transports\NclUSBSrv.exe
C:\Programmi\PC Connectivity Solution\Transports\NclIrSrv.exe
C:\Programmi\PC Connectivity Solution\Transports\NclRSSrv.exe
C:\Programmi\File comuni\Nokia\MPAPI\MPAPI3s.exe
C:\Programmi\Internet Explorer\iexplore.exe
C:\Programmi\File comuni\Microsoft Shared\Windows Live\WLLoginProxy.exe
C:\WINDOWS\system32\WgaTray.exe
C:\Programmi\Trend Micro\HijackThis\HijackThis.exe
C:\Programmi\Trend Micro\HijackThis\HijackThis.exe

O23 - Service: WLTRYSVC - Unknown owner - C:\WINDOWS\System32\wltrysvc.exe

--
End of file - 1819 bytes

scusa..... non me ne ero accorta

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 13.26.59, on 22/08/2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16705)
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\svchost.exe
C:\Programmi\Alwil Software\Avast4\aswUpdSv.exe
C:\Programmi\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\system32\HPConfig.exe
C:\Programmi\HPQ\Notebook Utilities\HPWirelessMgr.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\wltrysvc.exe
C:\WINDOWS\Explorer.EXE
C:\Programmi\Alwil Software\Avast4\ashMaiSv.exe
C:\WINDOWS\System32\bcmwltry.exe
C:\Programmi\ATI Technologies\ATI Control Panel\atiptaxx.exe
C:\WINDOWS\system32\carpserv.exe
C:\Programmi\File comuni\Real\Update_OB\realsched.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programmi\Nokia\Nokia PC Suite 7\PCSync2.exe
C:\Programmi\Alwil Software\Avast4\ashWebSv.exe
C:\Programmi\PC Connectivity Solution\ServiceLayer.exe
C:\Programmi\PC Connectivity Solution\Transports\NclUSBSrv.exe
C:\Programmi\PC Connectivity Solution\Transports\NclIrSrv.exe
C:\Programmi\PC Connectivity Solution\Transports\NclRSSrv.exe
C:\Programmi\File comuni\Nokia\MPAPI\MPAPI3s.exe
C:\Programmi\Trend Micro\HijackThis\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = about:blank
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 = Microsoft Internet Explorer fornito da CreaComputer.it
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = 127.0.0.1
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Collegamenti
R3 - URLSearchHook: Yahoo! Toolbar con blocco Pop-Up - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - (no file)
O2 - BHO: Supporto di collegamento per Adobe PDF Reader - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Programmi\File comuni\Adobe\Acrobat\ActiveX\AcroIEHelper.dll
O2 - BHO: WormRadar.com IESiteBlocker.NavFilter - {3CA2F312-6F6E-4B53-A66E-4E65E497C8C0} - C:\Programmi\AVG\AVG8\avgssie.dll (file missing)
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Programmi\Java\jre1.6.0\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
O4 - HKLM\..\Run: [Tweak UI] RUNDLL32.EXE TWEAKUI.CPL,TweakMeUp
O4 - HKLM\..\Run: [Cmaudio] RunDll32 cmicnfg.cpl,CMICtrlWnd
O4 - HKLM\..\Run: [ATIPTA] C:\Programmi\ATI Technologies\ATI Control Panel\atiptaxx.exe
O4 - HKLM\..\Run: [CARPService] carpserv.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: [Adobe Reader Speed Launcher] "C:\Programmi\Adobe\Reader 8.0\Reader\Reader_sl.exe"
O4 - HKLM\..\Run: [AVG8_TRAY] C:\PROGRA~1\AVG\AVG8\avgtray.exe
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [AliceRE_McciTrayApp] C:\PROGRA~1\ALICET~1\vendors\AliceRE\content\template\driven_dev\syncer\McciTrayApp.exe
O4 - HKLM\..\RunServices: [CPQDFWAG] C:\WINDOWS\Cpqdiag\CpqDfwAg.exe
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [Nokia.PCSync] "C:\Programmi\Nokia\Nokia PC Suite 7\PCSync2.exe" /NoDialog
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')
O6 - HKCU\Software\Policies\Microsoft\Internet Explorer\Restrictions present
O6 - HKCU\Software\Policies\Microsoft\Internet Explorer\Control Panel present
O8 - Extra context menu item: Add to Windows &Live Favorites - http://favorites.live.com/quickadd.aspx
O8 - Extra context menu item: E&sporta in Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office12\EXCEL.EXE/3000
O8 - Extra context menu item: Lookup on Merriam Webster - file://C:\Programmi\ieSpell\Merriam Webster.HTM
O8 - Extra context menu item: Lookup on Wikipedia - file://C:\Programmi\ieSpell\wikipedia.HTM
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\Office12\REFIEBAR.DLL
O9 - Extra button: Barra di ricerca di Encarta - {B205A35E-1FC4-4CE3-818B-899DBBB3388C} - C:\Programmi\File comuni\Microsoft Shared\Encarta Search Bar\ENCSBAR.DLL
O16 - DPF: {B8BE5E93-A60C-4D26-A2DC-220313175592} (MSN Games - Installer) - http://cdn2.zone.msn.com/binFramework/v10/ZIntro.cab56649.cab
O16 - DPF: {D27CDB6E-AE6D-11CF-96B8-444553540000} (Shockwave Flash Object) - http://fpdownload2.macromedia.com/get/shockwave/cabs/flash/swflash.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{58402A48-D69C-4B83-92BC-54FB6F66613D}: NameServer = 85.37.17.51 85.38.28.97
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: HP Configuration Interface Service (HPConfig) - Hewlett-Packard - C:\WINDOWS\system32\HPConfig.exe
O23 - Service: HPWirelessMgr - Hewlett-Packard Co. - C:\Programmi\HPQ\Notebook Utilities\HPWirelessMgr.exe
O23 - Service: ServiceLayer - Nokia. - C:\Programmi\PC Connectivity Solution\ServiceLayer.exe
O23 - Service: WLTRYSVC - Unknown owner - C:\WINDOWS\System32\wltrysvc.exe

--
End of file - 6686 bytes

Se ho visto bene,utilizzi Avast come antivirus.
Ti vorrei suggerire una scan online qui:
http://www.kaspersky.com/virusscanner
ed anche qui:
http://www.eset.com/onlinescan/
dove avrai un servizio in guanti bianchi.
Kaspersky rileva molto accuratamente,ma non cancella.
NOD32 invece può anche cancellare.
Questi software sono ottimi e,a mio giudizio,assai superiori ad Avast.
Magari potrebbero trovare altro che è sfuggito,e permetterti di migliorare le cose.
Saluti.

P.S.:
aggiungo che altre informazioni le potrai trovare in questo mio vecchio post,al quinto:
http://forum.aiutamici.com/Default.aspx?g=posts&t=52195

su task manager ho 7 voci uguali di SVCHOST.EXE che arriva fino a 100 e poi si abbassa di colpo..boh

No, non mi serve il log di CCleaner.
Hai fixato le voci di HijackThis ?
Hai eliminata la cartella AVG ?
Le 7 voci di SVCHOST.EXE possono essere normali, questa applicazione viene usata da molti programmi.
Quando apri il Task Manager, dopo il balzo al 100% a quanto si stabilizza la CPU ?
Altra cosa:controlla sempre nel Task Manager se trovi questo processo: avgtray.exe
Se lo trovi, lo selezioni , e clicca su Termina processo.

Beh.....è tutto normale mi sembra....
il 10% è accettabile.