If that doesn't work. Format the partition, with whatever partition manager you choose. I prefer Paragon Partition Manager. Once you have reformatted, insert a Windows XP (or Vista, although I don't use Vista, so I'm not sure if these will work.) CD, and go into the the REPAIR CONSOLE. Log into the console, and then use the following commands.
Got it all taken care of and formatting now. Comp finally booted from the XP disk. I had to rearrange the boot sequence. For some reason, going into the one-time boot menu and picking the cd drive wouldn't work.