Today, I was working in the computer, and decided to give a quick restart, no previous problems, unusual noises or otherwise, but on reboot "error loading operating system"

I have tried to read previous posts on the internet and are either too technical for me or don't seem to apply, but this is what I have tried so far

BIOS does recognize the drive
Exchanged with another HD with working XP and works, but obviously wants me to reactivate copy
OEM Windows XP disc does load> setup> Drive C is unformatted, damaged, or formatted with incompatible file system with options to format or return to previous screen......and that where I decided to stop and ask the experts before I really mess something up

My computer is a hodgepodge of parts, so not sure what to include
was using up to date Win XP
no recent hardware changes
to the best of my knowldge no untrusted software downloads
HD: Hitachi Deskstar 200GB

If you need anything else please let me know
Thanks

Update

I connected as an external and was able to determine the c: partition of the drive is unreadable, the D: is fine

Is there any way to recover this and how did it happen???

plz help no work will equal no job, any recommendatons????

I really wished someone would have helped, but we did find a solution and since this is a popular forum would like to post to hopefully help someone else out


Boot off Windows XP installation disk
Perform a Repair <R>
that will exit to the Window XP Recovery Console
select which installation you would like to log on to (almost always 1)
Enter Admin pass
the type 'fixmbr'
That was actually unsuccessful for me, but a must try

so type exit
it will reboot
<r>
Recovery Console
type 'fixboot c:' (if C is your non working drive)
are you sure? <Y>
type 'exit'
which reboots and now computer working as before

Thanks again to everyone, hope this helps others