Is just he mouse freezing or is the actual computer freezing? Are you able to type? Do your programs continue to run?
It might be that your processor and memory ar ebing used up and your computer lags in one area or another.
I have a Creative laser mouse. Lately the cursor freezes on the screen often. Moving my fingers or something else under the mouse does not help. I have to wait until it unfreezes by itself. I use XP.