Has anyone had trouble with their HDS units displaying "No Source" on the structure screens? My will stop working and say "No Source" and then start working again. It has usually only happend once maybe twice a trip. Today it did it a lot. Sometimes it would work fine and then it would start and stop, start and stop, start and stop (some of the stops will last for 10 minutes or longer) and then it work work fine again for awhile. The 2D works the entire time. Seems to be something with the structure scan. Has anyone seen this?