Laptop crashing/overheating?

Hello!

Right I've had my Acer Aspire 9302AWSMi for about 18 months now. I've only had the following problem for about the last 4 months.

When it crashes the screen turns off and about a second later the machine turns off. This happens with and without the power cable in.

It only happens when I'm doing certain things on the laptop it seems. Watching online videos (youtube, naughty vids etc) it'll crash after about half an hour. Playing games (Football Manager 09 is the only game I play) and it'll last about 10-15minutes. This has just happened twice again now. This was not an issue until about 4 months ago because I use to be able to play FM2009 for hours without any problems.

Other things, such as downloading files, using Photoshop, Firefox normally, even watching hours of TV via 4OD or downloaded files through VideoLan all are fine and will not cause the laptop to crash.

The temps have always appeared high (via Speedfan) even before it started crashing.

The laptop is usually just kept on my desk and the desk does feel very warm when I lift the laptop out. The vent where air flows outwards also gives out very hot air. It still crashes though even if it's on my lap, bed or even held in the air.

Below is a screenshot of what Speedfan displayed after I had turned the laptop back on after it had crashed.

About a second before the laptop crashes it will freeze (mouse will stop moving and keyboard will not work).

http://img2.imageshack.us/img2/4870/82995272.th.jpg

I'm at a loss, I can accept it's possibly overheating but why not crash when I do other CPU intensive tasks such as hours of VideoLan or Photoshop?

For the first 2 months of crashing instead of the screen turning off (and it does turn off, not just go black but totally switch off) it would come up with the following:

http://img23.imageshack.us/img23/1292/dsc02585g.th.jpg
http://img24.imageshack.us/img24/5199/dsc02586l.th.jpg

And would not swtich off, just stay with the screen like that.

Before it crashes the temps on Speedfan can go above 100 for the second Core reading and close to 50 for the HD0 reading.

The laptops ram has been doubled to 2GB (from 2x512mb to 2x1024mb).

Help!

Have you ever tried cleaning the fans, heatsink, etc.?
It sounds like it is overheating imo, though other than that cleaning I have no idea what else you can do. ;)

It sounds as if it is failing when you are running GPU intensive software.

Some GPU temps might confirm that, but in a laptop anything that creates more heat is going to cause problems throughout the system so even if those temps are ok it may trigger a problem elsewhere.

My first instinct is to go with what Ross has suggested.
Insidemylaptop might give you some pointers on how to do that.

I had a case like this once. I had to replace the CPU heatsink and fan. I did think it was the GPU at first but as Lynx said anything heating up in there will f@ck everything up. The thing was so dusty that the fan seized and caused the overheating within a few min.