#3
^ Stupid advice. I guess the usual bashing of Mar'07 ers.

Don't brute force it, if you break the screw then you have quite some work to follow up for.
Try just A LITTLE BIT of WD 40 to lube it up first, then try again.
otherwise, you can use basic physics, and somehow shrink the screw before unscrewing it.
(i.e. a cube of ice, but that would be stupid. Go use your brain and figure out something)