I figured I'd revive this thread, as something new happened.

I've still been running into the issue described. Fortunately, it's kind of rare since it requires opening two different projects at the same time at work. I open multiple projects at the same time at home quite often, but rarely at work, so the issue is rare.

And today, I spent some time hunting down a data problem using a test project, then opened the production project, moved the relevant code over...and the production project asked me if I wanted to save the changes I had just made, which I did, and then it unloaded.

All this time I was thinking that it would unload as a part of startup, but that's not the case. It fully loads, then unloads itself, but is aware if changes have been made in the few seconds that it was loaded. I don't believe this would be the case if it was the loading process itself that was failing. In that case, it wouldn't think it was loaded and wouldn't notice that the files displayed had changed. Instead, it is fully operational, it just unloads itself. It unloads itself properly, though, asking to save any changes if appropriate.

Does that suggest anything?