So last night I was using 4.0d B4 on my netbook looking for a recent layout, and as I was scrolling through the snapshots, I came across a Passage guide I did a day or so before. I clicked on it to remember what the passage was, but it did not load after a few minutes. I did not think much about it then, just chalked it up to netbook slowness, and went on to do other things.
But I today I tried to look at it again (on a different computer) and the snapshot is gone from the list.
I will see if I can recreate the issue, and then post a log.