ok i have a laptop that i replaced the power jack on it myself (yes i did it right i do this alot.) i tested the jack made sure it has a charge gains a charge and can run off the A/C powersupply everything was great until about a day later i was getting symptoms similar to overheating, my computer would just shutdown without warning and the bottom of my laptop would be very warm so i have replaced the thermal paste and cleaned out the heatsink /fans also reseated the memory could this be a bad CPU?, i have a P4 3.2 in my laptop so i know its not an energy efficient laptop made CPU. any advice anyone? im lost.

check your battery to make sure it is not getting excessively hot. If so, it may be failing and may require replacement. Bad batteries can get abnormally hot when charging. It is normal for them to get hot when charging, but not too hot.

i should have mentioned this but no my battery is not getting abnormally hot it actually isnt gaining a charge at all i can run off A/C power (until it shuts off anyway) but the battery does not take a charge.