Seems to me that you may be infected again.
You assume that you removed all malware on the drive...but did you ever boot that drive again? That would have been the only way to tell if you had indeed "removed all the viruses."
Then again...the drive could be dead...Windows XP balks at booting with dead drives attached or non-bootable devices like flash drives, external drives, etc.
From what you've stated so far...I'd say that you have a dead drive on your hands...until you can get some sign of life out of it.
I suggest trying to run the appropriate hard drive manufacturer's diagnostic (long test, if long/short are offered) and see what status it indicates.
Bootable Hard Drive Diagnostics - Vox - http://usasma.vox.com/library/post/bootabl...iagnostics.html
Hard Drive Installation and Diagnostic Tools - http://www.bleepingcomputer.com/forums/t/28744/hard-drive-installation-and-diagnostic-tools/
How to write a CD-DVD image or ISO - http://www.bleepingcomputer.com/tutorials/write-a-cd-dvd-image-or-iso/