Whenever I move the mouse the computer freezes. Reformatting the hard drive and reinstalling Windows does not fix the problem, neither does changing the mouse.

In your case I am pretty sure that there is a major hardware issue with your computer. Since formatting and reinstalling Windows did not fix the problem, we can generally rule out any software as the cause. However, it is quite strange that you are able to install Windows (as you would need to use the mouse) without any problems, yet when you attempt to use Windows when installed, there are these problems. If the problem was related to your hard drive, then this would generally be picked-up during the Windows installation. My best guess is the problem is caused by faulty RAM. I have been able to install Windows on computers which have the incorrect type of RAM installed and, while the installation goes successfully, there are some serious stability problems when attempting to subsequently use Windows. This is just my thoughts, as it is difficult to give a more definite diagnosis without looking at the machine. I suggest you take the computer to a technician, as this would be the best way to get the problem properly diagnosed and fixed.