Computor Crashes And Shows Error Messages

here is my log. I have run all spyware and virus control which shows nothing…please help

Logfile of HijackThis v1.99.1
Scan saved at 8:04:17 AM, on 5/26/2007
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16414)

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:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\arservice.exe
C:\WINDOWS\eHome\ehRecvr.exe
C:\WINDOWS\eHome\ehSched.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\WINDOWS\system32\dllhost.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\HP\HP Software Update\HPwuSchd2.exe
C:\WINDOWS\SYSTEM32\USRmlnkA.exe
C:\Program Files\Java\jre1.5.0_11\bin\jusched.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\WINDOWS\system32\ctfmon.exe
C:\WINDOWS\SYSTEM32\USRshutA.exe
C:\WINDOWS\SYSTEM32\USRmlnkA.exe
C:\PROGRA~1\mozilla.org\Mozilla\Mozilla.exe
C:\DOCUME~1\HP_ADM~1\LOCALS~1\Temp\Temporary Directory 6 for hijackthis.zip\HijackThis.exe
C:\DOCUME~1\HP_ADM~1\LOCALS~1\Temp\Temporary Directory 7 for hijackthis.zip\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.yahoo.com/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://www.yahoo.com/
N4 - Mozilla: user_pref("browser.search.defaultengine", "http://www.google.com/"); (C:\Documents and Settings\HP_Administrator\Application Data\Mozilla\Profiles\default\ip88zhoi.slt\prefs.js)
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\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:\Program Files\Java\jre1.5.0_11\bin\ssv.dll
O2 - BHO: hpWebHelper Class - {AAAE832A-5FFF-4661-9C8F-369692D1DCB9} - C:\WINDOWS\pchealth\helpctr\Vendors\CN=Hewlett-Packard,L=Cupertino,S=Ca,C=US\plugin\WebHelper.dll
O3 - Toolbar: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Program Files\Yahoo!\Companion\Installs\cpn\yt.dll (file missing)
O4 - HKLM\..\Run: [HP Software Update] C:\Program Files\HP\HP Software Update\HPwuSchd2.exe
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [USRpdA] C:\WINDOWS\SYSTEM32\USRmlnkA.exe RunServices \Device\3cpipe-USRpdA
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.5.0_11\bin\jusched.exe"
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKCU\..\Run: [Mozilla Quick Launch] "C:\Program Files\mozilla.org\Mozilla\Mozilla.exe" -turbo
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.5.0_11\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Sun Java Console - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.5.0_11\bin\ssv.dll
O9 - Extra button: (no name) - {e2e2dd38-d088-4134-82b7-f2ba38496583} - %windir%\Network Diagnostic\xpnetdiag.exe (file missing)
O9 - Extra 'Tools' menuitem: @xpsp3res.dll,-20001 - {e2e2dd38-d088-4134-82b7-f2ba38496583} - %windir%\Network Diagnostic\xpnetdiag.exe (file missing)
O17 - HKLM\System\CCS\Services\Tcpip\..\{8BBCB252-4AFE-4DBE-BB3F-51690F6D50A7}: NameServer = 207.69.188.187 207.69.188.186
O20 - Winlogon Notify: WgaLogon - C:\WINDOWS\SYSTEM32\WgaLogon.dll
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - ALWIL Software - C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: avast! Antivirus - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashServ.exe
O23 - Service: avast! Mail Scanner - Unknown owner - C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe" /service (file missing)
O23 - Service: avast! Web Scanner - Unknown owner - C:\Program Files\Alwil Software\Avast4\ashWebSv.exe" /service (file missing)
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe