Hi Tobias
bus errors can happen for many different reasons. You shouldn't worry about them unless they are very, very frequent. Having the unit on a clean and stable power feed is a good thing.
You can now try to force unloading the current preset. Reboot the unit and press & hold the PROGRAM key *when* you read H8000FW on the display. This will lead you to a prompt to loose the current preset and load mute. Choose YES.
Please let me know….
best
I
