I was trying to figure out some of the commands on the wiki (http://wiki.logos.com/Logos_4_Commands) -- when I got to "Set Sync to {Yes|No}". I tried it out but it did not do anything other than invoke a search.
So I pressed f1 and typed "set sync" into the search box, which brought up "set synchronization", on which I pressed Enter. That crashes L4. Repeatable.