Question : Problem: why would a mouse skip around after a few minutes of the computer running?

When this computer is on for like 20 minutes the mouse begins to skip around the screen instead of moving fluidly.  Like when i slide the mouse accross the screen it will jump about a centameter then pause then jump a centameter and jump again.  Its not moving on its own, its responding to me moving the mouse.  We did replace the mouse before,  and that made no difference.    im running win xp with norton also running.  

Answer : Problem: why would a mouse skip around after a few minutes of the computer running?

Did you see if anything was eating up the processor or the memory ?