mouse problems...

New to the forum, hoping someone can help out. I'll give you a brief summary of the situation.

I was using an imac- OSX(pre intel) desktop and loved it. Worked flawlessly for 6months to a year. All the sudden the mouse started tracking "funny". Shortly after the mouse would freeze from time to time. I would remedy the situation by unplugging the mouse (usb) and plugging it back in and restarting the computer. This worked fine until the problem got more and more frequent. I contacted a mac repair store and they advised I should try another mouse- I did.... same exact problems. I should mention I was using the mouse it came with. I was wanting to upgrade to a souped up mini anyway so I thought it would be a good time. The repair store said it was most likely the usb ports themselves that needed changed and that was $400.00 ish.. So I put the imac in the closet and have been enjoying my mini since.

Recently I had a thought.... the keyboard on the imac always worked flawlessly- and of course it's usb connected. So I dug the imac out and tried it again. Same problems.... Upon restart the mouse will work spuratically then freeze up. I did open up word and typed for a while and the keyboard worked fine. I've tried both mouse's (mice???) in different usb ports and had the same results. I even put the mouse in the keyboards usb port..let the computer go to sleep, and then I moved the mouse, clicked it and nothing... but I tapped the space bar one time and the computer woke up immediately.

I'd love to have this imac up and running as it's a nice machine and would be handy to have running. Any thoughts, similar problems or solutions would be appreciated- thanks in advance.