I have and averatec 4265 laptop with Vista. It was freezing badly. No viruses found. Ran tests and they showed Hard Drive writing slow or nothing and video card not working well. I got a new Hard Drive (ATA). After install it began to act the same, then it shut down and cannot find the HD. Tested HD and RAM and then tried again, same result. Bios cannot find the HD now even though it passed the tests. How can I determine if this is a hardware problem? Thanks for any help.