Hi Bob
How old is you B2?
Have you recently had your B2 open (at either end) ?
The problem could be cause by a loose connector - to check this - power the machine off and unplug it.
Then turn it over and remove the 2 front screws either side at the front,. Then with a little persuasion using a plastic (disposable picnic knife so as not to scratch the case) ease the front off . It will come away as a piece but will be still connected
to the innards of the B2 by a ribbon cable. Check that the plug at the end of this cable (where it connects to the front) is well seated. Then replace the front and see if this made a difference.
The next possibility could be some sort of corruption relating to the SD Card in your B2 or to the Operating System software on this card. To test this get a new SD Card and flash the Brennan software to it as set out following instructions on the
Brennan Web Site and or in this Forum.
If this does not cure the problem then perhaps your Screen is failing - You can get a new screen from Brennan's web site
and there are instructions on how to replace it.
If your B2 is still under guarantee I expect Brennan will sort this for you.
Fred