One Way Wireless Mighty Mouse

Just noticed that my mouse wheel only scrolls the page down, and not up.

Any ideas what is wrong?

Clean the roller wheel and it should work. Just rub it upside down on a damp cloth or a little alcohol

Or as someone else suggested here (sorry, I don't remember who) - turn it upside down and rub/scroll the ball in all directions while pressing down fairly hard on a clean sheet of paper on a flat surface. This has become my preferred way of doing it, and I am always amazed at how much gunk actually comes out. Works really quickly, and is easier than the other methods I was using (alcohol on swabs, etc).

Gee... your avatar is the same as one of my pals from a car forum.