hi, i want to know whatis the problem.

when i play almost 30 mins. my pc shuts down.

please answer.

It could be the temperature...
If ur cooler isn't fixed on the motherboard, or there isn't the necessary "Termic Mass" that white cream between the processor and the cooler...
Try to force ur processor, opening a lot of processes or something, if it shut down that's the temperature

One simple question that may be the answer to all your computer problems:

Is it a vista?

Currently Vista is almost as good as any other OS, most of the problems have been fixed. It's just that people blame common computer problems on Vista if they have it and pass with a shrug if not.
-Hopea

I am sorry... but you will have to euthanize your computer... just like how you euthanize the Weighted Companion Cube in Portal... jk
Try getting more ram or buying a bttr coolant system.

It's most likely overheating, my old laptop used to do that, just set a huge ass fan by it or something so it can get more circulation.

I too bet on cooling problems...

Do this, if you can:

if its a laptop:
1 - buy an active cooling platform (with fans) and place your laptop on top of it
2 - open the bottom of your laptop to clean its cooling system... I would recommend you to replace the termal grease.

I used to have overheating problems... so I did this to mine like 1 year ago and now it NEVER shutsdown due to overheating.

1. Simply try dusting you computer REALLY GOOD.
2. Restart your computer and press "delete" to go into BIOS in one of the menus it should say the core temperature if it's higher than 45C I believe, somebody correct me on the right temp for this, then buy yourself some thermal compound for 10$ and read a tutorial on how to PROPERLY apply it.

I think that a processor can get a little more than 45C...
I toasted my finger time ago, but it wasn't shuting down...

Yeah, an overheated proccessor could keep your computer from shutting down/ it will bluescreen/ it may do NOTHING. I'd clean it out and get some Arctic Silver Thermal compound, it's some of the best.

Check the temperature before you assume it's overheating... What's your hardware that will help, derp.