BAD_POOL_HEADER Error Message on Vista Home Premium

I'm trying to fix a custom built computer. When I received it I kept getting a blue screen so I replaced the 400GB HDD for a new 500GB HDD (no software on it, completely blank) and it still gave me the blue screen. At first the error was it has too much RAM (motherboard supported up to 2GB and it had 3GB) and now it keeps giving me a BAD_POOL_HEADER error and its driving me insane. I took the whole computer apart and put it back together and I'm still having that issue. Please HELP ME!!

Computer Specs:

*Custom Built
*Biostar 945GC-M7 TE motherboard
*2GB RAM
*500GB HDD
*Pentium Dual-Core process (I dont know how many GHz)
*450 Watt power supply

I really need you help. Thanks in advanced!

 

So you obviously re-installed fresh on the new HDD then??

 

Yes, I installed a brand new HDD. I found out what was causing the BAD_POOL_HEADER error message. The 2GB RAM card wasn't working. I left it with the extra 1GB RAM card it had and it started working perfectly. I just told the guy he needed to buy more RAM because the computer was running really slow wityh 1GB RAM.

 

Fair enough ... good to hear.

 

Thanks!