Unfortunately I did not save the log file before starting up Logos again to try to reproduce this, so all I have is the Logos4Crash.txt.
I had The New Unger's Bible Dictionary open in the left tile and Program Settings in the right (along with a bunch of other resources in other tabs). I had New Unger's scrolled to around the section of the transliteration table with Half-vowels (trying to see if changing the font to something else besides Default would fix the box that shows up there instead of a schwa -- see other bug report for that). First I selected Default Sans Serif, next Arial, and finally LRS System 1. When I clicked on the latter, Logos crashed. Here's a partial screenshot:

And here's the crash log: 12545.Logos4Crash.txt
Hopefully there's enough to go on in there to figure out what's causing the crash.
I have not been able to reproduce it, but if I do I'll post a full log file.