Is this a hardware or software problem?

[Agent Plissken]

Hey guys, please help!
When I boot my computer it goes to a blue screen that says there has been a REGESTRY_ERROR. It says if i have installed any new hardware to remove it. I havent installed any new hardware. I tried to boot from my DELL windows disk (i cant find my normal XP pro disk), I tried to fix the problem but it comes up saying that I dont have a hard drive installed. So I checked the BIOS and it has no hard drive detected.
I HAVE a hard drive installed, and when windows attempts to load it shows the splash screen (so it must be getting info from the hard drive right?)
It is a S-ATA if that makes a diff... PLEASE HELP, SOMEONE, ANYONE!!

[zippyjuan]

Did it somehow come unplugged (either at the back of the drive or at the motherboard?

[Agent Plissken]

nope...