i have a problem similar to yours.  at random times in both sp and mp, all of sudden, some of my mouse buttons and keyboard keys stop working right.  its always the key I have bound to crouch then the keypad keys.  the only thing that fixes it is a reboot.  even if i exit the game, the keys are still messed up.
I also have a explorer mouse, intellipoint 4 software.
------------------
   
 
    
if you can see us............then you're already dead
Ghost Soldiers, 6th Ranger Bn.
[This message has been edited by Cpt. dick (edited January 26, 2002).]