Windows 7 shuts down unexpectedly when I close my lid

I recently installed Windows 7 Professional x86, and recently when I close my lid my computer instead of going to sleep, which is what the power setting is set to, it shuts down. When I open my computer, I have to turn my computer on and when Windows loads, I get the 'Windows shut down unexpectedly' window. Has anyone heard of this happening or has had it happen to them or knows how to fix it?