Someone installed my copy of xp on their computer and activated it while i'm still USING the same copy  on MINE.
I understand one of our computers will have problems now, Which one?
If mine is the one that will have problems, what should i do if i can't get him to uninstall his?I have never heard of registration/activation causing problems... If you have used to CD before, then it shouldn't WORK on another computer due to the security device...

FlameIt is the upgrade home version and it is working on a second computer so far.Are you sure yours is activated? Are you positive the other one was?If you used the CD on both computers, I'm suprised it worked.

FlameIn my expierence Microsoft is pretty lienient with activating products, I would expect a little moreso with an upgrade. My guess would be that if you reinstalled it on one of the computers (or on a third) it may make you call them. Calling them is really simple, you read the numbers off the SCREEN, and if it doesn't like you, then you talk to a person who asks "is this installed on any other computers" You answer, they give you the key.

I wouldn't worry about it too MUCH, Microsoft isn't going to remotely detonate your computer or anything.