è un po' di tempo che il pc va lento, e si blocca facilmente! vi allego il log di HijackThis, c è quacosa che devo eliminare?
Logfile of Trend Micro HijackThis v2.0.4
Scan saved at 19:45:12, on 14/07/2012
Platform: Windows 7 SP1 (WinNT 6.00.3505)
MSIE: Internet Explorer v9.00 (9.00.8112.16447)
Boot mode: Normal

Running processes:
C:\Windows\system32\Dwm.exe
C:\Windows\Explorer.EXE
C:\Windows\system32\taskhost.exe
C:\Program Files\Common Files\Adobe\ARM\1.0\AdobeARM.exe
C:\Program Files\Avira\AntiVir Desktop\avgnt.exe
C:\Program Files\Common Files\Java\Java Update\jusched.exe
C:\Program Files\Samsung\Kies\KiesTrayAgent.exe
C:\Program Files\Malwarebytes' Anti-Malware\mbamgui.exe
C:\Program Files\Common Files\Spigot\Search Settings\SearchSettings.exe
C:\Program Files\Windows Sidebar\sidebar.exe
C:\Program Files\uTorrent\uTorrent.exe
C:\Windows\System32\spool\drivers\w32x86\3\E_FATICEE.EXE
C:\Program Files\Samsung\Kies\External\FirmwareUpdate\KiesPDLR.exe
C:\Program Files\Windows Live\Messenger\msnmsgr.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Program Files\Mozilla Firefox\plugin-container.exe
C:\Windows\system32\taskeng.exe
C:\Windows\system32\wuauclt.exe
C:\Program Files\Trend Micro\HiJackThis\HiJackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.google.it/
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 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant =
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
R3 - URLSearchHook: YouTube Downloader Toolbar - {F3FEE66E-E034-436a-86E4-9690573BEE8A} - C:\Program Files\YouTube Downloader Toolbar\IE\6.0\youtubedownloaderToolbarIE.dll
R3 - URLSearchHook: uTorrentBar_IT Toolbar - {4ae0c3d6-f713-4eed-bc65-25dc3ffdaac1} - C:\Program Files\uTorrentBar_IT\prxtbuTor.dll
O2 - BHO: AcroIEHelperStub - {18DF081C-E8AD-4283-A596-FA578C2EBDC3} - C:\Program Files\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll
O2 - BHO: uTorrentBar_IT - {4ae0c3d6-f713-4eed-bc65-25dc3ffdaac1} - C:\Program Files\uTorrentBar_IT\prxtbuTor.dll
O2 - BHO: Java(tm) Plug-In SSV Helper - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre6\bin\ssv.dll
O2 - BHO: Windows Live ID Sign-in Helper - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Common Files\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Program Files\Java\jre6\bin\jp2ssv.dll
O2 - BHO: YouTube Downloader Toolbar - {F3FEE66E-E034-436a-86E4-9690573BEE8A} - C:\Program Files\YouTube Downloader Toolbar\IE\6.0\youtubedownloaderToolbarIE.dll
O3 - Toolbar: YouTube Downloader Toolbar - {F3FEE66E-E034-436a-86E4-9690573BEE8A} - C:\Program Files\YouTube Downloader Toolbar\IE\6.0\youtubedownloaderToolbarIE.dll
O3 - Toolbar: uTorrentBar_IT Toolbar - {4ae0c3d6-f713-4eed-bc65-25dc3ffdaac1} - C:\Program Files\uTorrentBar_IT\prxtbuTor.dll
O4 - HKLM\..\Run: [Adobe ARM] "C:\Program Files\Common Files\Adobe\ARM\1.0\AdobeARM.exe"
O4 - HKLM\..\Run: [avgnt] "C:\Program Files\Avira\AntiVir Desktop\avgnt.exe" /min
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Common Files\Java\Java Update\jusched.exe"
O4 - HKLM\..\Run: [KiesTrayAgent] C:\Program Files\Samsung\Kies\KiesTrayAgent.exe
O4 - HKLM\..\Run: [Malwarebytes' Anti-Malware] "C:\Program Files\Malwarebytes' Anti-Malware\mbamgui.exe" /starttray
O4 - HKLM\..\Run: [SearchSettings] "C:\Program Files\Common Files\Spigot\Search Settings\SearchSettings.exe"
O4 - HKCU\..\Run: [Sidebar] C:\Program Files\Windows Sidebar\sidebar.exe /autoRun
O4 - HKCU\..\Run: [uTorrent] "C:\Program Files\uTorrent\uTorrent.exe" /MINIMIZED
O4 - HKCU\..\Run: [EPSON Stylus DX8400 Series] C:\Windows\system32\spool\DRIVERS\W32X86\3\E_FATICEE.EXE /FU "C:\Windows\TEMP\E_S32A4.tmp" /EF "HKCU"
O4 - HKCU\..\Run: [KiesHelper] C:\Program Files\Samsung\Kies\KiesHelper.exe /s
O4 - HKCU\..\Run: [KiesPDLR] C:\Program Files\Samsung\Kies\External\FirmwareUpdate\KiesPDLR.exe
O4 - HKCU\..\Run: [msnmsgr] "C:\Program Files\Windows Live\Messenger\msnmsgr.exe" /background
O4 - HKUS\S-1-5-19\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /autoRun (User 'SERVIZIO LOCALE')
O4 - HKUS\S-1-5-19\..\RunOnce: [mctadmin] C:\Windows\System32\mctadmin.exe (User 'SERVIZIO LOCALE')
O4 - HKUS\S-1-5-20\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /autoRun (User 'SERVIZIO DI RETE')
O4 - HKUS\S-1-5-20\..\RunOnce: [mctadmin] C:\Windows\System32\mctadmin.exe (User 'SERVIZIO DI RETE')
O8 - Extra context menu item: E&sporta in Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office12\EXCEL.EXE/3000
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\Office12\REFIEBAR.DLL
O10 - Unknown file in Winsock LSP: c:\program files\common files\microsoft shared\windows live\wlidnsp.dll
O10 - Unknown file in Winsock LSP: c:\program files\common files\microsoft shared\windows live\wlidnsp.dll
O11 - Options group: [ACCELERATED_GRAPHICS] Accelerated graphics
O23 - Service: Adobe Acrobat Update Service (AdobeARMservice) - Adobe Systems Incorporated - C:\Program Files\Common Files\Adobe\ARM\1.0\armsvc.exe
O23 - Service: Avira Pianificatore (AntiVirSchedulerService) - Avira Operations GmbH & Co. KG - C:\Program Files\Avira\AntiVir Desktop\sched.exe
O23 - Service: Avira Realtime Protection (AntiVirService) - Avira Operations GmbH & Co. KG - C:\Program Files\Avira\AntiVir Desktop\avguard.exe
O23 - Service: Application Updater - Spigot, Inc. - C:\Program Files\Application Updater\ApplicationUpdater.exe
O23 - Service: EPSON V3 Service4(01) (EPSON_PM_RPCV4_01) - SEIKO EPSON CORPORATION - C:\ProgramData\EPSON\EPW!3 SSRP\E_S40RP7.EXE
O23 - Service: MBAMService - Malwarebytes Corporation - C:\Program Files\Malwarebytes' Anti-Malware\mbamservice.exe
O23 - Service: Mozilla Maintenance Service (MozillaMaintenance) - Mozilla Foundation - C:\Program Files\Mozilla Maintenance Service\maintenanceservice.exe
O23 - Service: NVIDIA Display Driver Service (nvsvc) - NVIDIA Corporation - C:\Windows\system32\nvvsvc.exe

--
End of file - 6667 bytes

Segui il percorso ed elimina questo programma:
C:\Program Files\Common Files\Spigot\Search Settings\SearchSettings.exe

Chiudi tutti i programmi e disconnesso lanci HJT e clicca sul secondo pulsante: Do a system scan only poi metti la spunta alle voci che ti indico e alla fine clic su Fix checked:

R3 - URLSearchHook: YouTube Downloader Toolbar - {F3FEE66E-E034-436a-86E4-9690573BEE8A} - C:\Program Files\YouTube Downloader Toolbar\IE\6.0\youtubedownloaderToolbarIE.dll

R3 - URLSearchHook: uTorrentBar_IT Toolbar - {4ae0c3d6-f713-4eed-bc65-25dc3ffdaac1} - C:\Program Files\uTorrentBar_IT\prxtbuTor.dll

O2 - BHO: uTorrentBar_IT - {4ae0c3d6-f713-4eed-bc65-25dc3ffdaac1} - C:\Program Files\uTorrentBar_IT\prxtbuTor.dll

O2 - BHO: YouTube Downloader Toolbar - {F3FEE66E-E034-436a-86E4-9690573BEE8A} - C:\Program Files\YouTube Downloader Toolbar\IE\6.0\youtubedownloaderToolbarIE.dll

O3 - Toolbar: YouTube Downloader Toolbar - {F3FEE66E-E034-436a-86E4-9690573BEE8A} - C:\Program Files\YouTube Downloader Toolbar\IE\6.0\youtubedownloaderToolbarIE.dll

O3 - Toolbar: uTorrentBar_IT Toolbar - {4ae0c3d6-f713-4eed-bc65-25dc3ffdaac1} - C:\Program Files\uTorrentBar_IT\prxtbuTor.dll

O4 - HKLM\..\Run: [Adobe ARM] "C:\Program Files\Common Files\Adobe\ARM\1.0\AdobeARM.exe"

O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Common Files\Java\Java Update\jusched.exe"

O4 - HKLM\..\Run: [Malwarebytes' Anti-Malware] "C:\Program Files\Malwarebytes' Anti-Malware\mbamgui.exe" /starttray

O4 - HKLM\..\Run: [SearchSettings] "C:\Program Files\Common Files\Spigot\Search Settings\SearchSettings.exe"

O4 - HKCU\..\Run: [Sidebar] C:\Program Files\Windows Sidebar\sidebar.exe /autoRun

O4 - HKCU\..\Run: [uTorrent] "C:\Program Files\uTorrent\uTorrent.exe" /MINIMIZED

O4 - HKCU\..\Run: [EPSON Stylus DX8400 Series] C:\Windows\system32\spool\DRIVERS\W32X86\3\E_FATICEE.EXE /FU "C:\Windows\TEMP\E_S32A4.tmp" /EF "HKCU"

O4 - HKCU\..\Run: [KiesHelper] C:\Program Files\Samsung\Kies\KiesHelper.exe /s

O4 - HKCU\..\Run: [KiesPDLR] C:\Program Files\Samsung\Kies\External\FirmwareUpdate\KiesPDLR.exe

O4 - HKCU\..\Run: [msnmsgr] "C:\Program Files\Windows Live\Messenger\msnmsgr.exe" /background

O4 - HKUS\S-1-5-19\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /autoRun (User 'SERVIZIO LOCALE')

O4 - HKUS\S-1-5-20\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /autoRun (User 'SERVIZIO DI RETE')

O23 - Service: Application Updater - Spigot, Inc. - C:\Program Files\Application Updater\ApplicationUpdater.exe

Poi fai una pulizia con Ccleaner compreso il registro.

Installa Malwarebytes QUI lo aggiorni e poi fai una scansione COMPLETA non rapida, se trova qualcosa eliminalo.
Tieni deframmentato il disco.
Fai sapere se il pc migliora, ciao.