Well, first, I suggest you try another mouse. Primarily USB... Try a friend's mouse. I want to see if it's the mouse with the issues, or the computer. Also, as far as overheating... I have not heard of there being any issues with leaving your computer on overnight, or for several days. According to some articles I've read, leaving it on doesn't seem to cause damage to any components. In fact, they seem to suggest that powering them on, and then down again is worse, becuase the system must work harder to get things moving. For one, once the computer is on, the computer fans blow the dust out of the vents. Once you turn the computer off, the fans go off, thus allowing the dust to re-enter the system, which in the very long run isn't good. As far as overheating, if your fans are working right, I don't think it's an issue. Personally, if I left it on all week, I would at least restart it 1-3 times during that week, just to let the system refresh. It's always good to get more than one opinion on this. I have personally never heard of, or experienced any issues with leaving a computer on for most/all of the week, however, someone else might have something different to say. Stick with us for a bit, someone will be around to give their thoughts.