Try disabling Fast User Switching (in the Users Control Panel applet). I am
not a big fan of FUS because of the problems that I've seen.

For a more elegant fix, try this:
http://www.kellys-korner-xp.com/xp_tweaks.htm
Line #34 (left side)

I got the above suggestion from this thread:
http://www.bleepingcomputer.com/forums/topic31829.html

- John

"opuskitty" wrote:

> I have three desktops on my computer. Mine is the main and my kids each have
> one. It's fine when we switch from my desktop to theirs, but when we try to
> switch back my computer crashes. Can I fix this without deleting their
> desktops and starting over? Is there anyway to keep this from happening again?