Problem with switched mouse axis

[Repteror]

My friend managed to get his mouse axis switched: when you move the mouse foward, the cursor goes left, if you move the mouse left, the cursor goes up.
I have never seen anything like it.

The problem occured after restarting his pc, it seems he hadn't installed no new sofware or hardware, before that. This is a software problem(probably some settings altered), because the first time it happened a computer expert fixed it by changing something in the pc's(windows xp) options and without using extra software.

But now it occured again and i can't find any posts or tutorials regarding switched mouse axis.

Could somebody offer any advice or ideas on how could it be undone?

[ITJeremy]

I'd try removing the drivers for that mouse... restarting the pc with a different mouse and see what happens.. If all works, which it should. Then re-connect the other mouse and try again.