Games Keep Crashing

Hello. I'm new to the forum so I hope someone can help me, and I hope this is considered the correct section.

I have recently bought a new Gaming Vibox computer, and when I play any games, after about 15-20 minutes the game crashes, freezes or minimizes to 3/4 screens.

I have had the error message 'Amd Driver stopped responding and has recovered' show up numerous times, but it doesn't always.

I have checked all my drivers are up to date and am just wondering what else I can do? Been searching the internet for a few days and still can't find a solution. It happens with every game I play - Skyrim, Football Manager, Company of Heroes!

My computer specs are:

Processor: AMD Athlon(tm) X4 750K Quad Core Processor, 4000 Mhz, 2 Core(s), 4 Logical Processor(s)
Graphics Chipset : AMD Radeon HD 6450
RAM: 8gb

Running windows 7 32 bit

Sorry I know you'll need more information on computer but my minds gone blank staring at it wondering what you'll need to know!!!!

I hope someone can help please, it's infuriating me!!

Thanks.