xp immediately logs off after logging on

[six mile mountain]

as soon as I log on to xp it logs off - I've tried it with normal logon, as
guest, administrator, in safe mode, safe mode with networking, safe mode with
command prompt - each time it just cycles back to the log on screen

this happened after running norton anitvirus 2009

any suggestions?

 

[Anteaus]

There are various reasons for this, one is a corrupted userprofile, another
is that the 'userinit' value in the winlogon registy key has been changed to
point to a nonexistent handler-program. Fixing the latter is quite tricky,
and typically involves booting from BartPE and using a remote-registry
editing tool.

The other option is a repair install.

http://www.michaelstevenstech.com/XPrepairinstall.htm

Note that the repair install is NOT the 'recovery console' option, it comes
later in the setup process.