MacBook over heats and stops while in sleep mode

(if this isn't the right thread, forgive me. I'm a newbie. We'll all survive one way or another. /: )

Alright.

My title may not be that helpful so I'll explain. Sometimes, when I put my computer in sleep mode, I'll leave the room for less than ten minutes (usually more), I'll come back and my computer will be overheating like crazy for five seconds and stop (stops for a shot period also)... Overheat....stop....overheat...stop...I'm pretty sure you get it. I don't know if repairing my disk permissions will do any justice (It's helped sometimes I guess), so, well, what is the problem? (I do shut off any running programs when I put it in sleep mode)

Sorry if this isn't quite explanatory.

Something process must be running out of control. Check Activity Monitor in your Utilities Folder.