I'm going to describe my situation in the best way I can.
I have a Dell D520
here are the specs:
Processor: Intel Core Duo T2300E 667Mhz Dual Core
Display: 14.1 inch XGA LCD Panel
RAM: 512MB, DDR2-533 SDRAM, 1 DIMM
Hard Drive: Hitachi 100GB, 7200RPM
Optical: Sony 8X DVD+/-RW
Wireless: Intel PRO/Wireless 2200 802.11a/g WLAN
Battery: 6 Cell Primary Battery
For the past two months, the laptop has been turning itself off supposedly after it overheats. However, I've used Speccy, OCCT and Speedfan and sometimes it turns itself off with motherboard temps of 40-50c. Sometimes the laptop turns it off as soon as I open the top from 'sleep' mode.
Also it doesn't always turn off. Sometimes it almost goes into hibernation with the power light still on and my unable to press any key.
I must admit I have installed quite a few programs including Firefox, Skype, Spotify, Itunes and numerous files.
Look at the performance stats and compare with my other laptop(which works fine) and is a Dell D620. Both laptops are only running OCCT and a youtube page on Firefox.
I ran the test for 17-18 secs and notice how the values of the D520 vary much more in the same time frame to the bottom one.
I have also ran an anti-virus that did not pick up anything but I used AVG's one click maintenance and the problem was gone for a week but as since returned.