Forum Moderators: bakedjake
fdisk first, and delete all the old partitions. Create a new primary partition using the whole disk (or split the disk as required), then you should be able to reformat the drive. Another thing to remember is to restore the master boot record if you had LILO (the Linux bootloader) installed. To do that, you should run the command
fdisk /mbr at the DOS prompt - there is no confirmation, but once the DOS prompt reappears, it has worked. Hope that helps!