Hello George,
hard to say, I can only speculate and ask some questions.
Maybe the drive propagates a type, which is not supportd by Windows Home Server. In this case it would be an option, to create a job (either based on ntbackup or on robocopy script or something similar) to backup the contents of this drive to a shared folder on your WHS.
You already tried the option to click
Configure Backup in the WHS console with the PCMCIA drive active in the laptop to get it detected?
Also what is the power save status in device manager for drive/controller? Does it work better, if you disable the option that the computer may power off the device to save power?
What for a label has the volume on the disk? In
one thread has been reported, that the volume name "Data" causes a similar misbehavior (new disk detected, but declared as not eligible for backup).
Best greetings from Germany
Olaf