Computer freezing

OK, my specs are as follows:

2x500GB Hard drive
2.5ghz AMD Athlon x2 processor
4GB DDR2 RAM
512MB Nvidia 8500GT graphics card
750W PSU
The system is approximately 10 months old

OK, the story started a few weeks ago when i had problems with my computer randomly shutting down. I narrowed the problem down to either my PSU or my graphics card. My graphics card looked broken (the fins beneath the card had a massive amount of movement in it, much more than it did when i bought it 15 months ago.) I bought a new 750W PSU and it solved that problem, i haven't had it happen since.

Last Wednesday i decided (as i wanted to do for a while) to reformat my hard drive and start using my second 500GB Hard drive. It was all fine until Tuesday. I ran a virus scan, and cleaned out 90 or so cookies. I installed Windows Live Messenger (the latest version) and watched a movie. The next time i tried to log in, i had a lot of troubles.

My computer failed to start up properly. I kept having it stall on startup. Occasionally i would get a disk read error. At first i thought it had to do with the weather (we've had almost two foot of rain this week) and the humidity. Yesterday i started my computer up and i've managed to get in, but whenever i use the internet, my computer starts to freeze up. It's ok whenever i visit a low graphics-intensive webpage, but as soon as i visit a page like http://www.skyscrapercity.com/showthread.php?p=36981606#post36981606 , my page freezes up, as does my entire computer and i am forced to turn it off at the powerboard. I am not sure what the problem is, i think it is my graphics card. Can anyone weigh in on this, provide some assistance to solve it.

Thanks in advance

 

Check your RAM ... i worked on a machine today with the exact same problem and she had a stick that wasn't in properly.

 

Also if your getting disk errors after installing a new HDD, you should check that out too, but i agree with Drizzles, that the RAM stick does seem like the likely problem