bluetooth link-key corrupted

Hi.

My BB Pearl 8100 with firmware 4.2.1 is used in order to pair with a bluetooth receiver (industrial application).
After pairing process the link-key is created and the receiver name is append to the paired devices list on BB.

In the next days the BB is used to connect to the bluetooth receiver. It is working ok in general, using the existing link-key. Eventually it may have some error in one connection.

If we achieve six or seven times with error, the link-key is turned corrupted. If we remove the link-key and we try to create one more time, it is not working. Turning-off and after turning-on the bluetooth on the BB is not a solution.
The only solution is the BATTERY PULLING.

Is there any other solution in order to avoid the annoying battery pulling?
Maybe, some security configuration?
Help is wellcomed.
Thanks.