I had a lockup today and my thought is to clean up by reloading firmware, presets setlists and IRs, that way if a bit or two has fubarred it will get cleaned up. When you update/reload the firmware there is a checksum/verify of the bianaries to make sure that they are loaded correctly. A while ago during 2.53 update I lost a setlist and did not have the presets backed up and ended up loosing some presets, one was a favorite. The setlist export corrupted during the file compression part, I think. I now make sure that I back up all three ways individual preset, setlist and full export.
I may have caused my lockup problem in mine by switching crap barefoot and changing a delay from ms to 1/2 trip on the fly while running the looper.