Running WInXP Pro.  Clean install just a few weeks ago.  Have installed all updates, etc.  Have activated Windows built-in firewall.  Had a virus within first few minutes on internet, so eliminated worm, and turned on firewall.  Think I have another one, based on behavior of Windows.

When I log on, Windows IMMEDIATELY shuts down (1 min. countdown) - no time to access online virus scanner, etc and correct

Error message I get is:  "C:Windows/System32/sass.exe terminated unexpectedly with status code 128. . . . . .

Can use WindowsXP in Safe Mode without computer shutting down.  "Have run Adaware to check for spyware/adware - none found.  PandaSoftware PQRemove.exe can't find any viruses (abbreviated program).  How can I access internet in Safe Mode in order to go to a thorough online virus scanner?  Is there a way to dial out and access internet in Safe Mode?  My ISP connection program does not want to run in Safe Mode.  Can anyone help?  Does anyone know what virus/worm this might be causing this problem.  When computer shuts down on it's own (after the 1 min. countdown, due to this problem), when I try to log back on it asks for a logon password (none installed).  If I power down and reboot, I can go into safe mode, or attempt to log in normally without the password interference.  Any assistance would be apprciated!