Apple BT keyboard not typing?

At least on my mac. It works on my roommates, however.

On Saturday evening I just couldn't type on the thing. Turned BT on and off. Put in new batteries.

The arrow keys to scroll work. I can Apple+Tab. But the letters don't work. Additionally, my mac becomes extremely sluggish (to the point where I apple-option-esc to close safari and/or finder) and that's when my mac kind of unlocks something.

Any ideas on how to get it to work?

Any suggestions?

 

Yes I have tried that already.