can not log on to user accounts

using xp home edition
at the windows welcome screen, users, I click on any user; says loading your settings, then it logs right off, says saving your settings. same thing happens in safe mode or any other mode. I can't get in to do any thing. How can this be fixed?

 

This is usually caused by a virus (technically a peice of spyware) that alters the userinit logon file. The PC runs fine with the spyware installed, but if you remove the spyware by running a scan of some type (like AdAware for example), it leaves a corrupt userinit file behind. You can try this:
http://www.winxptutor.com/wsaremove.htm
Read info that starts about a third of the way down... look for the green text that says "Phase III....". You should probably familiarize yourself with the whole article so you know what you're (probably) dealing with since you'll be doing "Phase II" also (after Phase III which is a bit off, I know). If you can access drive C: (either from a PE CD or maybe the recovery console), read Phase I and try it. The "regsvr" part probably won't work, but renaming the offending DLL file should help the situation. If you don't have the .DLL, it may have been removed by a spyware scan, or you have a different infection than the one outlined in the article.
NOTE: this isn't the only malware that causes the symptoms you describe, but it is one of the most common. There's no guarantee it will work. But it can't hurt to try

 

Thanks, but I couldn't get it to work.