Can't Move Issue! Help!

[Pouncing_Zebra]

Someone please help! I've been playing UMS2 perfectly fine on my macbook pro for a week or two now to show them mods, so my friends decide to make a server on Big Dig. We can all connect fine, but when I'm in i can move for roughly 5-10 seconds (if I'm lucky) then my keyboard stops working. I can't jump, move, inventory, pause the game with escape, etc.- I have to press command+space to look up another program which automatically pauses minecraft then i disconnect or I can unpause, play for 5 seconds then repeat. I CAN look around and hit blocks. This also happens in single player (not the server). Please help! Thanks!

[The Uber Cannon]

Sticky keys?