Netgear NAS RN3138 Drive Rack Mount. Users randomly loose connection to a mapped drive

Yesterday our Netgear ReadyNAS 3138 updated to firmware 6.9.2. Since then users have experianced a loss of connection of mapped network drives. If you reboot the NAS, all the connections are restored. But later they randomly break again. You can always ping the NAS drive from the PC in question. All users are affected at the same time. Attached is an extract of the log file.

The error message on the local pc's is "An error occurred while reconnecting P: to \\SKAIGH-RACK-NAS\Production. Microsoft Windows Network: The local device name is already in use. The connection has not been restored."

Any help solving this will be gladly received..........