mouse loads intermittently

`Whenever the computer boots up, there is a chance that mouse won't

boot up. This problem started happening the last two months. I have

used two different mouses and the problem is still there. I have tried

different USB ports.

I went into hardware devices and deleted drivers and replugged in

mouses and its 50 50 whether the mouse will boot up.

I have checked for new drivers and there is none. They say vista has

the latest. Mouse is working now after I changed port again

Maybe I have to reinstall XP and Vista.

Can anybody advise how I go about this in some kind of order or advise

solution.

Roger