Repeated 4 times now (with some minor differences):
1) Opened Logos.
2) Opened Passage Analysis (which opened to the Cluster Graph).
3) Clicked on Word Tree (which already had a previous search entered).
4) Spinning beach ball and crash.
Note: this previous search was probably done as late as May 5th, without problems. The only difference I can think of is that it didn't open to the Cluster Graph then.
Logos4 log: 0167.Logos4.log.zip
Apple crash log: 5314.Logos Bible Software 4_2011-05-08-164949_deleted.crash.zip (I have the previous ones as well, if you want them.)
EDIT: I finally, after another couple of crashes, managed to get away from the crashing by clicking Compare Pericopes before Word Tree.
It is still very annoying, however, that every time I open WT I have to first wait for a previous search to finish, before I can start the one I want to do. Even if I remove the search and leave the boxes empty before I close, there is still a search there when I open up again! And not only that: when I've changed in the first box, Logos immediately starts producing a new WT, before I've had time to change anything else. Which means that before I finally get the WT I want, I've had to wait for something like 2-5 other WTs to populate... A procedure that can take several minutes. Please make the WT open with the Bible etc set as last time, but the boxes empty. (Feel free to add a History dropdown at some later time, when you've dealt with more urgent matters.)