FC5 installation failing

[Dean S. Messing]

I downloaded the five CD images for FC5 in June and am finally
getting around to installing it.  I'm a Mandriva refugee and it's
my first ever FC install, though I've been reading this list
off-and-on for several months.

I'm having trouble right out of the shute.  After choosing
packages and hitting "next", it starts resovling package
dependecies.  Then up comes the error popup:


    An error occurred unmounting the CD.  Please make sure you're
    not accessing /mnt/source from the shell on tty2 and then
    click OK to retry


I go over to tty2 and make sure I'm not accessing /mnt/source,
come back to the install, and hit OK.  The error repeats.

The only slightly non-standard thing I did was to choose a custom
disk layout just before package selection.  I had already
partitioned and pre-formatted my disks under Mandriva before starting
the install.

I've now tried to install thrice with the same error message.  Can
anyone help me out here?

Dean