The install disks (xxx-RHEA-1999-044/045) cannot load /RedHat from either a NTFS (on a primary partition) or fat (on an extended partition). At the prompt for the location of /RedHat, neither partition appears as a choice. Even if the update disk does resolve the problem, it doesn't help because the installer won't prompt for the update disk until AFTER it's located /RedHat! By copying /RedHat to my existing linux root partition, I was able to get the update disk loaded. I then tried backing up to the screen where you select the location of /RedHat, but the install program aborted at that point. At the least, the installer should support loading /RedHat from a fat filesystem on an extended partition...
The installer was never meant to recognize source files on an NTFS partition, so that is not really a bug. We know that there are problems with the extended partitions, and it actually related to extended partitions of type "f" as opposed to the usual type "5" We are going to be putting together another update which will fix this problem, but until then the easiest workaround is to change the type of the extended partition from type "f" to type "5", upgrade your system, and then change the partition type back to "f". *** This bug has been marked as a duplicate of 6482 ***