Harddrive detection issues on windows xp?

hello, i am trying to reformat my laptop from windows xp media center to windows xp home edition. but evrey time i boot the computer with the xp cd inside, everything seeming ly goes fine until i get to the part when its actually about to reformat. cause when it tries to reformat, an error message pops up, saying that it cant detect the harddrive...any clues as to what might be going wrong?