[AccessD] Error: . . . Placed In a State . . .

I have three customers with similar large systems, and with two of them the
same error comes across in the error log from time to time.  The error
description is:

The database has been placed in a state by user 'username' on machine
'computername' that prevents it from being opened or locked.  (3734)

>From the error log, I can tell that this is happening when the FE is trying
to read from or write to the BE.  Any thoughts on what could be causing
this?


Thanks!
Dan