I never ended up getting a response from my ticket, but I think I may have fixed it on my machine. I reinstalled an older version of Evernote, which still had the same error but much less frequently. Through lots of trial and error (and crashes) I managed to narrow it down to the crashes being most frequent on a single note. It would crash consistantly whenever I tried to sync the note, or occasionally when I tried to open it. In version 5.0.3 it crashed on load because that was the note I was trying to load on startup. I ended up fixing the problem by using the older version to divide the note into three smaller notes each with 1/3 of the content and then deleted the old note (using right click->delete rather than selecting the note). This seems to have fixed the problem though I haven't tried to combine the smaller notes back into a large one. Since the crashes were really frequent this took a lot of trial and error and I still had to fix the problem a second time on my other machine which was still trying to read the old note (since it would crash if it tried to sync). For that one I had to select another note, then sync (which caused a crash) and then restart it which somehow preserved the old sync and had the new split notes in it. The note that was causing the problem used a lot of the checkbox markups and I was adding to it every day for about a year so I would guess maybe it was some kind of combination of those factors which caused the crash. I hope that helps you.