I'm not sure what the solution would be exactly, but I thought I'd let you know that there IS a way to go through the boot process on Mandrake and RedHat systems one test at a time, which makes it a lot easier to see what failed, etc.
I can't remember offhand how to do it either, as I haven't run either distro forever. Might be something for you to think about looking into though, so you can post the exact errors you're getting.
Have you tried mounting the partitions after the boot process, just from the console?
Try '$ mount -t FAT32 /dev/*** /mnt/Windows'
Just replace *** with whatever the windows partition is installed to.