Vista - Virtual Server 2005 hangs on restart with saved guests

Windows 2003 Enterprise R2 SP2 x64
hosting Virtual Server 2005 R2 SP1
12 guests running Windows 2003 Enterprise R2 SP2 x86

All guests are saved (through a VBS script). The host is restarted.
Virtual Server service appears to start normally. 20 seconds later, on
schedule, it starts the first guest. It logs event 1091, allocating memory
for the guest.

Then it hangs. No further log entries. Neither the web admin page nor
scripts can connect to the service. It doesn't respons to requests made over
connections created before it hangs. Sometimes a chunk of memory appears to
have been assigned to the first guest, usually not. The service does not
respond to stop requests.

Then I kill the process. Then start the service.

It then functions normally. (Except it often thinks the guest which was
only partially started is using a duplicate MAC. The guest has to be
restarted to have working network connection.)

(Sometimes it will fail again, this time locking up when the second guest
starts. Killing the process the second time, and starting the service again
then works. I don't think I've ever had to do it three times in a row.)

This doesn't happen if the guests are shut down rather than stopped.
This sometimes happens if the guests are saved and then the service restarted.
It always happens if the guests are saved and then the host OS is restarted.

This happens on several (but not all) of my (theoretically) identically
configured x64 hosts. I don't believe it is happening on any of my
identically configured x86 hosts.

Any ideas?

Thanks,
Tim C