Nut won't unscrew

[rste11]

I'm trying to remove my CPU heatsink and fan so I can replace the thermal grease, but one single nut refuses to unscrew. It just spins freely regardless of the way I turn it. I tried to pull up on the heat sink a bit so I might be able to get it to move down a little but it hasn't been working.

What do I do?

 

[nna2]

the screw spins freely? or the screwdriver cant spin it?
if the screw is what's spinning just pull the heat sink off

 

[rste11]

That actually just kind of worked. Thanks!

 

[rste11]

Best answer selected by rste11.