Processor Scaling Down

[Antimatter3009]

My laptop is a Dell Inspiron 600m that just today started acting up. I've been playing games on it (specifically, Rome: Total War) for about a week straight now (ah, vacation) and it's been fine. However, today I started playing and after a few hours of play it started to skip frames and generally be slow. So I looked around and found out that my processor had scaled back to 600Mhz (max 1.8Ghz). I let it sit for a bit and it went back up, so my first thought is an overheating issue. However, that would be strange considering it's been working fine for so long now. I can't think of anything else though, and I'm not sure what to do. Does anyone have any ideas?

 

[tsn | spazz]

Was your battery completely charged?

 

[Antimatter3009]

Yeah, and it's plugged in. Also, I tried to use SpeedswitchXP to force it to max and it still falls back.