Got an update this morning.
After restarting Logos4, instead of loading to layout (which I have set by default), Logos4 opened to a blank page. When I opened the home page, it populated appropriately. I switched back and nothing.
I tried manually loading the last layout (not saved) before closing. Logos4 paused, gave the "Not Responding" message in the title bar and reverted to a blank layout. Then I waited for a while, just to see if it would load eventually, and checked my log file for anything there (not that I know what to look for).
Finally I clicked to load the last layout from last night. L4 finally loaded my layout.
I'll include the Logos4.log, in case it tells anything interesting.
8168.Logos4.log
After shutting down Logos4, uploading my log and restarting, L4 opens to the previous layout, as I wanted.