VDDK Hang on Mounting Windows Volume

I have a customer who is getting repeated instances of VDDK hanging on a

vixMntapi_MountVolume(handle, read_only). We are logging information output by VMware, and the log contains the following:

.. Opening virtual disks successful...

05/28/2012 20:27:30 (info) DiskLibProvider_GetDisk: Open successful - index 0.
05/28/2012 20:27:30 (info) DiskLibProvider_GetDisk: Open successful - index 1.
05/28/2012 20:27:30 (info) Copying registry hive from \\.\vstor2-mntapi10-shared-F67766A9000010000000000006000000\\Boot\BCD to C:\WINDOWS\TEMP\vmware-SYSTEM\vixmntapi3.
05/28/2012 20:27:30 (info) [LoadTempHive] Registry hive C:\WINDOWS\TEMP\vmware-SYSTEM\vixmntapi3 is loaded under the name mntApi358269972130227761
05/28/2012 20:27:30 (info) Error 13 reading Element value from key mntApi358269972130227761\Objects\{9dea862c-5cdd-4e70-acc1-f32b344d4795}\Elements\24000001
05/28/2012 20:27:30 (info) Unloaded hive mntApi358269972130227761
05/28/2012 20:27:30 (info) DeleteHiveLogs: Deleted 1 hive log file on cleanup.
05/28/2012 20:27:31 (info) Copying registry hive from \\.\vstor2-mntapi10-shared-F67766A9000010000000000006000000\Windows\system32\config\SOFTWARE to C:\WINDOWS\TEMP\vmware-SYSTEM\vixmntapi3.

... and hangs there for 30 minutes. We restart after that. I have verified that the C: drive is not out of space, so does anyone know what exactly "copying registery hive" means and why it would hang doing this? I verified that there is indeed a vixmntapi3 and vixmntapi3.log in the vmware-SYSTEM directory.

Thanks,

Rich