Internet closes and cant download some programs

I just recently did a fresh install on my desktop due to having a virus, and now its worst sometimes when i am online the internet just shuts down. This happens both with Internet explorer and with Mozilla Firefox and another issue is when i try to download some programs it downloads them but they do not end up working. Here is my log from hijackthis if any one can help i would appreciate your help

Logfile of HijackThis v1.99.1
Scan saved at 5:05:40 PM, on 5/24/2009
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP1 (6.00.2900.2180)

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\Lavasoft\Ad-Aware\AAWService.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Lavasoft\Ad-Aware\AAWTray.exe
C:\WINDOWS\system32\RUNDLL32.EXE
C:\Program Files\SUPERAntiSpyware\SUPERAntiSpyware.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\wscntfy.exe
C:\Program Files\Windows Media Player\wmplayer.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Documents and Settings\Owner\Desktop\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = http://us.rd.yahoo.com/customize/ie/def ... earch.html
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://us.rd.yahoo.com/customize/ie/def ... .yahoo.com
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.yahoo.com/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://www.yahoo.com/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://us.rd.yahoo.com/customize/ie/def ... .yahoo.com
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Bar = http://us.rd.yahoo.com/customize/ie/def ... earch.html
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://us.rd.yahoo.com/customize/ie/def ... .yahoo.com
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.yahoo.com/
R1 - HKCU\Software\Microsoft\Internet Explorer\SearchURL,(Default) = http://us.rd.yahoo.com/customize/ie/def ... .yahoo.com
R3 - URLSearchHook: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\PROGRA~1\Yahoo!\Companion\Installs\cpn\yt.dll
O2 - BHO: &Yahoo! Toolbar Helper - {02478D38-C3F9-4efb-9B51-7695ECA05670} - C:\PROGRA~1\Yahoo!\Companion\Installs\cpn\yt.dll
O2 - BHO: Java(tm) Plug-In SSV Helper - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre6\bin\ssv.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: SingleInstance Class - {FDAD4DA1-61A2-4FD8-9C17-86F7AC245081} - C:\PROGRA~1\Yahoo!\Companion\Installs\cpn\YTSingleInstance.dll
O3 - Toolbar: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\PROGRA~1\Yahoo!\Companion\Installs\cpn\yt.dll
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [Ad-Watch] C:\Program Files\Lavasoft\Ad-Aware\AAWTray.exe
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKCU\..\Run: [SUPERAntiSpyware] C:\Program Files\SUPERAntiSpyware\SUPERAntiSpyware.exe
O4 - HKCU\..\Run: [MSMSGS] "C:\Program Files\Messenger\msmsgs.exe" /background
O4 - HKCU\..\Run: [Messenger (Yahoo!)] "C:\Program Files\Yahoo!\Messenger\YahooMessenger.exe" -quiet
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O20 - Winlogon Notify: !SASWinLogon - C:\Program Files\SUPERAntiSpyware\SASWINLO.dll
O23 - Service: Lavasoft Ad-Aware Service - Lavasoft - C:\Program Files\Lavasoft\Ad-Aware\AAWService.exe
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe

Look at the event viewer for errors.
Start, run eventvwr.msc press enter.

I do not see any errors around the time it happen : /

The log you posted looks clean. Download, update & run anti malware from malwarebytes.org If it doesn't find anything, run ipconfig /all from a command prompt & post the output.