Lost Disk Drive after "Hibernate" or "Standby"

Whenever I put the system to sleedp via hibernate or
standby, I lose a disk drive when I wake the system up.
The way I regain access to the drive is to reboot (that
is, do a complete shut down). Simply restarting the
system does not bring the drive back. Specifically, the
drive disappears from Windows Explorer, Device Manager
and any every other way that I know to look at a device.
The problem isn't fatal since I can always shut down and
reboot (or never put the system to sleep), but this is a
pain in the system.

The data on the drive is clean and remains available
until after the next hibernate/standby. I am running XP
Media Center Edition on a Sony Vaio PCV RZ46G.
Everything else seems to work according to specs.