Vista - Can't start Windows Vista (hard drive isn't recognized?)

Hi.

Suddenly, my computer freezed (just like it has been doing for some time now).
When I restarted it, the computer asked for the Vista DVD, so that it could repair some files (I couldn't even boot into Safe Mode). I put the DVD inside the drive, and choose the "Repair your computer" option, but it reports that no Vista installation is found...

I then boot into the Rescue and Recovery environment (that is a Thinkpad suite, located in another partition of the disk) to see what's going on.
The System Information detects everything except the Hard Drive (it reports "Not Available" for the fields "Hard disk free space" and "Hard disk capacity"). I also can't see the harddisk in the option to backup the files to a pen (the pen is recognized, though).
Just to be sure, I run PC Doctor and my hard disk passes all tests.

What's going on? How can I fix this? Help.

My harddisk is: hitachi hts722020k9sa00 fde ata device

So, I tried using the Vista Retail DVD one more time, just to be sure.

I chose the "Repair your computer" option and selected "Next", even though, no hard drive appeared in the list. Luckily, it worked, anyway. Weird.

All is well, now.