I have recently built myself a new computer and installed Windows XP. The mouse won't work. I plug it in the USB slot. The light on the bottom of the mouse glows, but the pointer on the screen doesn't move. I tried plugging the mouse into a different USB slot, but nothing happens. I even tried a different mouse, and no success either. However, my USB keyboard works perfectly. I have no idea why the mouse won't work. Any ideas?