Question : Problem: Laptop shuts down at different times?

I have an Emachines M5310 Laptop. This laptop seems to be having heat issues. For several months it has been shutting down whenever my kids try and play any games that tax the CPU in any way, but seemed to run fine when accessing the internet or even watching a DVD movie. Within the last week the shut downs begin to happen all the time sometimes within the first minute or two of booting. At other times it would run for 30 minutes to an hour before suddenly shutting off. I have opened up the laptop and pulled the heat sink and fan (all one unit) checked to be sure every thing is clean and working. I blew out all dust and reapplied thermal paste and reset the heat sink. I did not remove and reseat the AMD M CPU because I was not sure how to release the processor from the bracket. After doing this I rebooted and the problem is just as bad as before. Some things I have noticed are that when ever it shuts down it seems that the fan ramps up to high rpms just before she shuts down. I have also noticed that after shutting down like this I have too press the power on button twice before the laptop will power up. The first time I push the power on nothing happens at all. When I press it a second time it starts up. I moved the laptop out to my garage overnight (its cold out there). I went out and tired to boot it up this morning and on the first try it shut down before it could even load windows. On the second try it booted to windows and ran for about 30 minutes long enough to complete a spyware scan before shutting off. I'm starting to think that this might not even be a heat issue because of this type of inconsistent behavior. Any  suggestions for possible causes would be of great help.

Answer : Problem: Laptop shuts down at different times?

I picked up an M5300 unit last year that was having the same issue. The problem in that unit was a heat sink issue. I had to send it in to Emachines for repair as I was still under warranty. If only just barely.