Sleep Issues: Overheating, Fans Overrun, Won't Wake in this State.

Hey Guys,

I have a late 2010 MacBook Pro 15" which has been running fine up until today.

I rarely turn the MacBook off, just close the lid and let it sleep.

Today, I came back after a few hours of it sleeping and found that is was really hot, the fans really loud and wouldn't wake up when I opened the lid.

I had to hold the power button to restart. The sleep light was pulsing like it was sleeping, even after opening the lid.

Was wondering what could have caused it and if there is any app that I could run to see what was using the hardware while the MacBook was sleeping?

Thanks in advance.