Sounds like a power supply overheating to me....
The fan may be ready to quit for good, I have had a couple of P.S. fans quit and then work again for a while...
I also have had P.S. fans go out after just a few weeks of use, and if you don't shut down soon after you can start to "smell" trouble, it will be too late...
I would keep a keen ear on the P.S. fan for any funny noise, and if possible, put your hand behind the case at the P.S. fan exit every once in a while just to feel if the fan is still working, and that the air comming threw is not real hot.....
I hope you find and get this problem fixed before any xpensive damage is done...
ALSO About the Battery, IF it is the one about the size of a Quarter, I have had those be bad on a MB right out of the Box !
Good Luck..
SeeYa
