[N1lavKwr]

I dont know as much as you know but i tried formatting the system reserved partition after formatting bt5 partition and voila it worked out. I think grub was stored in the system reserved partition so when i formatted the partition it got removed. I dont know if your systems are using system reserved(OEM) partions but my system does so its worth a try. I used win7 disk to do it...
Regards,
N1lavKwr