Grey Screen during internet surfing windows 7

[green541]

Aspire x133
I bought an Acer computer about 1 1/2 ago with windows vista installed. It is a small profile desktop where the video card is built into the board.  I received windows 7 by mail as a free upgrade. After upgrading with Windows 7, my computer and especially my internet experience is unstable.

I will be online for a few minutes, and then get a grey screen. The problem can occur in different programs, but most likely when you are online using firefox or IE or doing something like watching a video clip. When I reboot, the problem reoccurs.

I sent this computer back two times to the manufacturer and they claim it is fine (they find no errors) , but the problem reoccurs. I also sent it to an independent computer repair place last week where they checked the system,reformatted the hard drive, reinstalled all software, but the problem continues. I would like to know what the most likely issue is. In the past, I've personally reformatted the hard drive and tried installing Windows XP, Vista, and Windows 7, but the problem continues.

I'm thinking it may be a conflict between the video and the operating system. The video is an NVIDIA NForce MCP78692BGA. I guess could also be a bad motherboard, bad ram, or bad hard drive, or something else. I'm searching for what would be the most likely way to proceed. If you search on Google, there are other Acer users with the same computer with similar problems, no one seems to have a clear answer. Can you please provide me with an answer??? The service manual for my PC is online at http://support.acer.com/acerpanam/Manuals/acer/2010/ServiceGuides/SG_Aspire_X1301_BOOK.pdf if that provides any helpful detail as system specs are in the back starting on pg 95.

Thank you

[Transfusion]

The MCP78 chipset has a GeForce 7025 as its onboard graphics, which is absolutely terrible by today's standards. Has issues with 1080p. I strongly suggest you upgrade it.
It would be ideal if you could get your hands on another working computer and swap out the parts individually to troubleshoot, of course.

Run http://www.memtest.org for 10 passes to check the stability of your RAM.
Run http://www.xtremesystems.org/forums/showthread.php?197835-IntelBurnTest-The-new-stress-testing-program Intelburntest on Standard to check for CPU stability. Also works with AMD processors.
You can get a cheap HD 5450 on newegg for testing (and upgrade):
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125314

Does the entire screen suddenly turn grey? Does it always happen when you are doing something video-intensive?
Windows 7 and its flowery Aero graphics effects will tax an older system like yours.