Database still locked after user closes application.

A registry entry on the server that can affect this behaviour:

HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\ Parameters\
DormantFileLimit

Determines how many files on each share can remain open in the redirector's
cache after an application has closed them. If the number of open, cached
files on a share exceeds the value of this entry, the system begins to close
the cached files.

Also
AutoDisconnect
Determines how long a client will remain connected if idle. If the client
breaks the connection instead of closing, this setting is one which
determines how long the server will have to wait before scavenging broken
file connections.
Conversely, this may effect a live database connection over lunch: I don't
know about that. Default value is 10-15 minutes. The least of the
client-server setting breaks first, the matching client setting is
KeepConn

(david)