Regensburg syndrome. Could be a firmware issue, if it's been updated. Or it might cure it if you do update the firmware/maps.
Basically, Regensburg is the default GPS position of the RNS unit, so any time it loses its memory or suchlike it defaults to Germany until it finds a valid GPS signal and recalculates. Try a new GPS antenna, or reposition the one you have, see how you get on with that. Also, when you have the unit pulled out make a note of the part number and suchlike on the top, as you could need it if you do have to update the firmware at a later date.