Certain sites cause browsers to stop working

[KingCookie]

Hi everyone, newbie here...I am running on Windows 98, and use both IE and Firefox as my browsers here at work (on a network). There are several sites that I frequent throughout the day, and recently, they not only are no longer accessible to me, but they cause me to have to reboot my CPU, as both browsers and my e-mail ceases to work afterwards. Needless to say, this is a major annoyance, as I keep in touch with several distant family members and friends throughout the country via these sites. I doubt that the sites have been blocked- both because our "IT guy" is clueless, and because neither site is an offensive one that would be deemed to be NSFW...also, we are given fairly free usage of the internet here, especially on our lunchtimes and breaks.

I had a scare with a virus recently, and I'm concerned that it wasn't removed effectively or that perhaps something was damaged in the process. My Norton discovered a virus about a month ago entitled "HacktoolSCKeyLogger" located in "C:\fun.exe", and said that it quarantined and deleted the virus. I then proceeded to update and run both AdAware and Spyboy S&D scans, neither finding anything more harmful than cookies. I then got desparate and purchased PC Mighty Max to do a check of my registry, which it found over 100 things wrong with, and supposedly repaired. Nope, still not working.

I have checked from other computers on the network, and none of them have a problem whatsoever. I've continued doing virus/spyware scans every day since then, and for ONE DAY everything was working perfectly (though nothing was found in any scans)...then, just as suddenly, I had to reboot and was back to square one.

Any ideas or help would be much appreciated...I've done everything I can possibly think of...thank you.

[KingCookie]

Just to be sure, here's a Hijackthis log taken just now...don't bite my head off...

Logfile of HijackThis v1.99.1
Scan saved at 1:50:17 PM, on 4/4/06
Platform: Windows 98 SE (Win9x 4.10.2222A)
MSIE: Internet Explorer v6.00 SP1 (6.00.2800.1106)

Running processes:
C:\WINDOWS\SYSTEM\KERNEL32.DLL
C:\WINDOWS\SYSTEM\MSGSRV32.EXE
C:\WINDOWS\SYSTEM\MPREXE.EXE
C:\WINDOWS\SYSTEM\mmtask.tsk
C:\WINDOWS\SYSTEM\MSTASK.EXE
C:\WINDOWS\SYSTEM\KB891711\KB891711.EXE
C:\PROGRAM FILES\COMMON FILES\SYMANTEC SHARED\CCEVTMGR.EXE
C:\PROGRAM FILES\COMMON FILES\SYMANTEC SHARED\CCSETMGR.EXE
C:\PROGRAM FILES\NORTON ANTIVIRUS\IWP\NPFMNTOR.EXE
C:\WINDOWS\EXPLORER.EXE
C:\WINDOWS\TASKMON.EXE
C:\PROGRAM FILES\COMMON FILES\SYMANTEC SHARED\CCPD-LC\SYMLCSVC.EXE
C:\WINDOWS\SYSTEM\USBSAFE.EXE
C:\WINDOWS\ANVSHELL.EXE
C:\PROGRAM FILES\COMMON FILES\SYMANTEC SHARED\CCAPP.EXE
C:\WINDOWS\SYSTEM\SYSTRAY.EXE
C:\PROGRAM FILES\PC MIGHTYMAX\PCMM.EXE
C:\WINDOWS\SYSTEM\WMIEXE.EXE
C:\PROGRAM FILES\COMMON FILES\SYMANTEC SHARED\SNDSRVC.EXE
C:\PROGRAM FILES\OUTLOOK EXPRESS\MSIMN.EXE
C:\WINDOWS\SYSTEM\PSTORES.EXE
C:\PROGRAM FILES\MOZILLA FIREFOX\FIREFOX.EXE
C:\WINDOWS\SYSTEM\DDHELP.EXE
C:\PROGRAM FILES\MICROSOFT OFFICE\OFFICE\WINWORD.EXE
C:\WINDOWS\SYSTEM\SPOOL32.EXE
C:\CETBIN\RUNW32.EXE
C:\PROGRAM FILES\MICROSOFT OFFICE\OFFICE\GRAPH9.EXE
C:\PROGRAM FILES\ADOBE\ACROBAT 5.0\READER\ACRORD32.EXE
C:\WINDOWS\TEMP\HIJACKTHIS.EXE

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.yahoo.com/
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Local Page =
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Local Page =
R3 - URLSearchHook: (no name) - {0894FF00-F6F5-430a-8915-2327EE763E88} - (no file)
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\PROGRAM FILES\ADOBE\ACROBAT 5.0\READER\ACTIVEX\ACROIEHELPER.OCX
O2 - BHO: NAV Helper - {BDF3E430-B101-42AD-A544-FADC6B084872} - C:\Program Files\Norton AntiVirus\NavShExt.dll
O2 - BHO: (no name) - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHELPER.DLL
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\SYSTEM\MSDXM.OCX
O3 - Toolbar: Norton AntiVirus - {42CDD1BF-3FFB-4238-8AD1-7859DF00B1D6} - C:\Program Files\Norton AntiVirus\NavShExt.dll
O4 - HKLM\..\Run: [TaskMonitor] C:\WINDOWS\taskmon.exe
O4 - HKLM\..\Run: [AtiPTA] Atiptaxx.exe
O4 - HKLM\..\Run: [Ati2cwxx] Ati2cwxx.exe
O4 - HKLM\..\Run: [AtiCwd32] Aticwd32.exe
O4 - HKLM\..\Run: [CriticalUpdate] C:\WINDOWS\SYSTEM\wucrtupd.exe -startup
O4 - HKLM\..\Run: [Symantec Core LC] C:\Program Files\Common Files\Symantec Shared\CCPD-LC\symlcsvc.exe start
O4 - HKLM\..\Run: [Symantec NetDriver Monitor] C:\PROGRA~1\SYMNET~1\SNDMON.EXE /Consumer
O4 - HKLM\..\Run: [MCI USB Safe ] [SystemFolder]usbsafe.exe
O4 - HKLM\..\Run: [MCI USB Safe] C:\WINDOWS\SYSTEM\USBSafe.exe
O4 - HKLM\..\Run: [anvshell] anvshell.exe
O4 - HKLM\..\Run: [ccApp] C:\Program Files\Common Files\Symantec Shared\CCAPP.EXE
O4 - HKLM\..\Run: [SystemTray] SysTray.Exe
O4 - HKLM\..\Run: [mdac_runonce] C:\WINDOWS\SYSTEM\RUNONCE.EXE
O4 - HKLM\..\Run: [ScanRegistry] C:\WINDOWS\scanregw.exe /autorun
O4 - HKLM\..\Run: [AtiQiPcl] AtiQiPcl.exe
O4 - HKLM\..\Run: [PCMMRealtime] C:\PROGRAM FILES\PC MIGHTYMAX\pcmm.exe /R
O4 - HKLM\..\Run: [QuickTime Task] "C:\WINDOWS\SYSTEM\QTTASK.EXE" -atboottime
O4 - HKLM\..\RunServices: [SchedulingAgent] mstask.exe
O4 - HKLM\..\RunServices: [HC Reminder] hc.exe
O4 - HKLM\..\RunServices: [KB891711] C:\WINDOWS\SYSTEM\KB891711\KB891711.EXE
O4 - HKLM\..\RunServices: [ccEvtMgr] "C:\Program Files\Common Files\Symantec Shared\ccEvtMgr.exe"
O4 - HKLM\..\RunServices: [ccSetMgr] "C:\Program Files\Common Files\Symantec Shared\ccSetMgr.exe"
O4 - HKLM\..\RunServices: [NPFMonitor] C:\Program Files\Norton AntiVirus\IWP\NPFMntor.exe
O4 - HKLM\..\RunServices: [ScriptBlocking] "C:\Program Files\Common Files\Symantec Shared\Script Blocking\SBServ.exe" -reg
O12 - Plugin for .spop: C:\PROGRA~1\INTERN~1\Plugins\NPDocBox.dll
O16 - DPF: {7B297BFD-85E4-4092-B2AF-16A91B2EA103} (WScanCtl Class) - http://www3.ca.com/securityadvisor/v...fo/webscan.cab
O17 - HKLM\System\CCS\Services\VxD\MSTCP: NameServer = 207.173.225.3,207.173.224.3