There is a problem with Mandrake 10 and Fedora Core 2 (caused by the 2.6 kernel) which uses the partition table a little differently to windows - I had this exact same problem and it is fairly easy to resolve if it is what I think it is.
I know grub (I learned it because of this problem) so if you are using grub paste the output of /etc/grub.conf (or /boot/grub.conf depending on distro).
If it is the problem with the way the 2.6 kernel messes with the partition table it can be resolved by doing the following as root:
sfdisk -d /dev/hda | sfdisk --no-reread -H255 /dev/hda --force
I booted into a Knoppix live-CD to do this to make sure, just su to root and it will give you the correct access, and this only applies if you installed to bootloader to the MBR of hda.
I highly recommend pasting the contents of your lilo.conf or grub.conf file first before you try that though - even though it isn't damaging, It's worthwhile making sure if it isn't something much simpler.