Windows 7: bizarre issue

To start off, I had Windows 7 Professional loaded and working on a HP dv6700CTO. I upgraded from Windows Vista Ultimate.

I had Windows 7 working for about two days until one morning I opened my laptop lid and it gave me a black screen with the error "Operating System not found." I started the laptop up again and it got to the screen stating Starting Windows and just hung there. I tried to reinstall Windows 7 from the original bootable flash drive that I used and when I get to choosing the hard drive to install/format, It can't detect my computer's hard drive. I then tried using a vista dvd to to access my hard drive but it hangs on a black screen with only the mouse pointer appearing after "Windows is loading files." Every now and then the same thing happens when using the Windows 7 flash drive. I'm not sure if this is an issue with my hard drive or something else, I just received this hard drive as a replacement for a failed one a day prior to installing Windows 7.



Any help would be much appreciated

Sounds like a bad hard drive. What is the brand?

Seagate Momentus 500GB