Could you give a little more information? I'm assuming that you currently have only one partition on the hard drive, and it is the boot partition? Are you doing the partitioning using windows disk manager, or some other utility? In general, the problem could come from the fact that it sounds like you're trying to use ALL of the available space for this other partition you're creating, which would leave your boot partition with no extra space... that could be what's causing your problem. Try lowering the amount of space you want for the other partition, and see if that helps.