Windows Won't Boot

It seems like it's been forever.  In reality it has been a couple of months since my Windows XP will not boot on my Dell Desktop.  I've done everything I could and the people at Microsoft thought, could solve the problem.  It's still there.  NOW THIS IS IMPORTANT TO UNDERSTAND:

My Dell powers up, then it goes to the Windows start-up screen.  Then it says "Diskett drive 0 seek failure".  Well I do not have a diskett drive.  I've gone into Dell and tried to change the order of the boot to no avail.  Like I said I've done everything I and Microsoft could think of.  To the extent that if I wasn't smart enough I'd have downloaded one of the worlds worse viruses.