Vista - Random hibernation - please help!

I'm having a REALLY annoying problem. Quite simply, my laptop hibernates randomly without warning when I'm doing something!

I'm running a Vista Home Premium on an HP Pavilion dv2000 laptop (it came with vista) and I started noticing the problem when I started playing Tomb Raider Underworld, and it would just randomly hibernate. The thing gets REALLY hot when I play games so I just assumed it was some kind of overheating problem, because it didn't hibernate so much when I took breaks from playing it.

But how overheated can it get when I'm just surfing the net?! It hibernated 4 times on me yesterday and I felt like taking an axe to this thing!! :@

I even tried turning off the hibernation option through the command prompt, but that didn't help - instead of hibernating, it shut off completely! The screen just went black and instead of taking a minute to save everything to memory, it just turned off completely! When I restarted the laptop it started up as usual, with no error message or anything. (I re-enabled the hibernation option after that)

I read somewhere that it was possible to disable the shutdown option through the group policy settings, but when I tried to open up the settings, I got this message:

MMC cannot open the file C:\Windows\system32\gpedit.msc.
This may be because the file does not exist, is not an MMC console, or was created by a later version of MMC. This may also be because you do not have sufficient access rights to the file.

At one point I tried using the Windows memory diagnostics tool, just for the heck of it to see if there was something wrong. I have no idea what happened - it said it would restart when the scan was done so I went off somewhere but when I came back the thing had turned off.

Is this an overheating problem or is it something else? I mean I noticed some odd things about my Vista - for one thing when I bought the laptop the help and support stuff never worked until I upgraded to SP1. I'd really love some help on this!

Home Premium has no gpedit (M$ uses it as another means to convince ppl to buy the pricier Ultimate version)
you'd have to google the right options and enter them into the registry by hand

But that wouldn't solve your problem.
If it's really caused by overheating, try to clean the insides (canned air etc), take back any BIOS changes (overclocking ?) and make sure the air circulation isn't blocked etc.

-DG

Have you tried setting "Turn my computer to sleep" to "never" in the power options?

I think I did try turning off the sleep option once but I'm not sure if it did any good.

Take back the BIOS changes? Erm... I'm not really tech-savvy on this so I don't really know how I would do that...

My laptop hasn't hibernated on me all day (didn't do any changes to it) but I just noticed something I never did before after carefully looking at the base of the laptop. If anyone else has an HP Pavilion could they tell me what exactly is in the compartment in the middle? The one directly below the battery compartment with the chip-looking symbol on it? Because whatever it is, it's bulging (i.e. the cover for it isn't completely closed because whatever is in there has expanded or something) and I know that definitely isn't normal! Haven't opened the screws or anything yet out of fear of messing something up...