Last holiday my Zumo 500 started to freak out after 4 years and 40.000km, couldn't select anything and it started to randomly make new favorite locations.
Too bad I was 1100km's away from home and it happened in the first of 3 weeks holiday.
I made it home without any problems, but it was a long ride without my MP3 music
Last week I ordered a new screen + digitizer in Hong Kong (I didn't want to mess with just replacing the digitizer).
Hopefully this will fix the problem.
Still thinking about selling it and buying a new Garmin Zumo 660...