Hard Drive preventing booting

I've got a situation that has completely puzzled me, wondering if anyone can help.

My friend asked me to fix her laptop, which has been failing to boot, getting as far as the blue Windows 7 login screen then hanging. The login UI doesn't load, it's just the blue background.

I tried to re-install Windows from the boot disc, but when I put in the disc, I wasn't able to boot from it. Instead the computer booted from the hard-drive again and hung at the same place. This is after changing the boot priority in the BIOS.

Since the laptop is out of warranty, and is to all intents and purposes a brick, I removed the Hard-drive, and connected it to my computer to see if I could reformat the drive from there. The thing that has really puzzled me though, is that my computer wouldn't boot when this hard drive was attached, despite running fine before I attached the drive, and after I removed it.

Which leads me to think there's possibly a really malicious virus or something on the drive, which makes it the default boot device, despite having a corrupted operating system installed that won't boot.

Has anyone heard of anything like this in the past, or have any ideas for a possible solution?

The laptop is a Sony VAIO PCG-71312M, and the hard drive is a Toshiba MK5065GSX.

I'd be wary of removing and reformatting the drive - it should almost certainly contain a recovery partition from which you should be able to recover the system drive and/or burn a st of recovery dvd's. Have you tried booting to the recovery partition?

It's an MBR issue. Plain and simple.

"A Master Boot Record (MBR) is a special type of boot sector at the very beginning of partitioned computer mass storage devices like fixed disks or removable drives intended for use with IBM PC-compatible systems and beyond. The MBR holds the information on how the logical partitions, containing file systems, are organized on that medium. Besides that, the MBR functions as an operating system independent chain boot loader in conjunction with each partition's Volume Boot Record (VBR)."

I have tried the recovery partition, but nothing happens when it's selected, it just boots to the same place and hangs again. Since it's a friends computer, and she isn't particularly savvy, she didn't think to keep the recovery discs in a safe place, and now has no idea where they are.

@ELiTEFX

2 questions.

First, why would the MBR affect a different computer which already has it's own MBR, and casue the same issues?

And secondly, how would you go about fixing an MBR issue?

As explained specifically above, each hard drive has it's own MBR onboard. Do a thorough Google search to understand what role the MBR plays and it's possible recovery. Folks pay BIG bucks to recover data trapped on an HDD with a corrupt MBR.

Easy fix: trash the hard drive and buy another. It's a Brick.....................

OK, sorry for the misunderstanding:P

I thought that would probably be the case, just wondered if there was a fix before I spent the money.

Thanks for the help

get a linux live cd. (xubuntu) it will boot the pc and has disk utility's that will fix the disk. Then reload MSOS. Its free iso img burn to cd. All data will be lost!