My daughter has a Dell Dimensions 8400, it has been working fine.  It has the wireless key board and mouse.  It was working fine.  All of a sudden, the mouse wasn't working.  I replaced the battery and it did not work.  Now both the mouse and they key board are not working.  When I hooked up a key board from an older machine, the key board worked, but the mouse did not.  Does anyone have any suggestions?