Vidhya, Sugesh, Martha,

Those were very good suggestions and I appreciate all your thoughts going into them.  However, I checked them out but they were not the problem, either.  I have authority...

Thanks for the suggestions, but that does not seem to be it:

Sugesh - no quotas are enabled on any of the disks.

SQLBill - no other specific tasks are running to lock...

SQLBill,

No, the space is not 'locked' because the computer is sitting idle at the time.  I am suspicious of a bad disk controller on the server, but I have no...