esegui Hijackthis, clicca sul tasto "Do a system scan only", spunta le seguenti voci e clicca su "fix Checked"

R3 - Default URLSearchHook is missing
O2 - BHO: IEHlprObj Class - {01FB9C55-FC66-4476-A199-389241193188} - C:\WINDOWS\system32\MxCFCHYM.dll (file missing)
O2 - BHO: (no name) - {6F8DDADA-D71B-450C-B894-D86251EEC844} - C:\WINDOWS\system32\vtULcdAp.dll (file missing)
O2 - BHO: (no name) - {C10A35BF-49B3-4D18-A2A6-1FF122683FE1} - (no file)
O2 - BHO: (no name) - {F3BEA1B2-6285-41AD-8399-03D04518B1AE} - (no file)
O2 - BHO: (no name) - {FEE322BB-081A-43AF-91BF-1F89ECD67DFF} - (no file)
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Programmi\Java\jre1.6.0_05\bin\jusched.exe "
O4 - HKLM\..\Run: [QuickTime Task] "C:\Programmi\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [NeroFilterCheck] C:\Programmi\File comuni\Ahead\Lib\NeroCheck.exe
O4 - HKCU\..\RunOnce: [] C:\Programmi\Internet Explorer\iexplore.exe http://www.symantec.com/techsupp/ser...oductMessages? *****
O9 - Extra button: (no name) - {16930DCA-0910-4C00-86FF-0C73872D4ABA} *****
O9 - Extra 'Tools' menuitem: cerca sul web - {16930DCA-0910-4C00-86FF-0C73872D4ABA} *****
O9 - Extra button: ***** - {2B44FD33-B048-4B2B-88D5-4B80AB018F29} *****
O9 - Extra button: cerca sul web - {810B72CB-566A-409B-B6A3-31F720C16FAE} *****
O9 - Extra button: (no name) - {A2199168-22AC-44A3-BA5F-8A83E693FEBF} *****
O9 - Extra 'Tools' menuitem: ***** - {A2199168-22AC-44A3-BA5F-8A83E693FEBF} *****
O9 - Extra button: InstallareKazaa - {EF6D6AE3-2625-40D6-A5AB-920DFD2DAF8C} *****
O9 - Extra button: ***** - {F4445FEB-6D20-47CB-9ACF-9D142A7F680A} *****
O9 - Extra button: (no name) - {FF55FC7B-F2EB-4F50-9409-2F726DD0E112} *****
O9 - Extra 'Tools' menuitem: ***** - {FF55FC7B-F2EB-4F50-9409-2F726DD0E112} *****
O20 - Winlogon Notify: vtULcdAp - C:\WINDOWS\
O23 - Service: Gestione P&P Plus (pppcntl) - Unknown owner - C:\WINDOWS\downlo~1\qho2\420tke6u.exe (file missing)
ho coperto con gli asterischi la parte restante perchè inutile; ora è più semplice individuare le voci da fixare. Vedi di non saltarne nessuna.

Poi riposta nuovamente hijackthis, per piacere.

Ciao