I had the same problem after I updated my FLARM firmware this year. I made the mistake of using the same memory stick that had last year's update on it. The problem was solved when I reloaded using a formatted stick with only the update on it. I also reloaded my config file from a previously formatted stick.

BUT: For some reason the problem still briefly re emerges when I fly near certain military installations. I don't understand why that happens - and it's only intermittent.
ROY