Hi
Yes - I had the Navaid updates from www.aero.sors.fr. When I removed them, the problem with the gauge went away. Unfortunately it was replaced by another one of crashing after inserting the waypoint to the plan, however I fixed that by following the advice you had given to someone in another thread to add:
ProvideAIdata=Yes
ProvideAIairports=No
to the [General] section of FSUIPC4.ini
So the gauge now works for me.
Many thanks for helping so quickly