Help, please!! XP logon auto logoff

I had a virus, got rid of it. Then I think the computer said I had an update to install... now, when I try to logon, I get what appears to be a normal start up. However, I click logon then the system automatically logs me off. I've tried the F8 screen - safe mode, safe mode command prompt, pretty much all options in the f8 screen and nothing works. ACK! I could really use some help. By the way, I don't have an XP disc as my husband got this pc from his former employer for $50! Hoping someone has the answer that'll make my day!

 

i have the same problem, i hope it gets sorted.