When you have a drive that is messed up, Linux MBR and windows doesn't like it, switching Operating systems, getting rid of old data, or for whatever reason I find it handy to pop in a linux live CD like knoppix and issue
Code:
dd if=/dev/zero of=/dev/hda bs=1M
(Substitute your drive parameters)
That will zero the drive from start to end. It will take a few minuets depending on drive size.