Getting error when installing OS

[SurfHigh]

Hi guys, my build is:
mobo - DH67BL
pro - i5 2500
with 4GB ram and 500GB HD.

The problem began 2 weeks ago. I had my running windows 7 64b. While watching movie suddenly I got the blue screen. It became more often until yesterday, then I thought i'll just re-install win 7 64b.
right in the beginning of the installation, after I already erased all partions , I get an error 0xC0000007.
I thought it might be the win7 version so I tried another one. Same result.
I even tried to install ubuntu 11.04 that was already running successfully on this specific PC in the past - the installation just got stuck, pretty much in the beginning too.

Looks like this a hardware problem, but I really don't know.
Help please!

 

[voyagerfan99]

Run Memtest86+ and test your hard drive. It sounds like one of those might be defective.

 

[SMGOwnage]

It may also be your CD/DVD drive. I think it sounds more like a RAM and/or HDD error.

 

[SurfHigh]

OK, found the problem. One of the memory sticks stopped working.
I used windiag.