All of the SendMessage stuff is normal. In the console, run keepass in the background.
Then find the process
ps ax | grep KeePass
then when it freezes, send the QUIT signal to that process
kill -QUIT <pid>
where <pid> is the process number from above
This should give a stack trace of where it is hung up.
Also, if you have any plugins, make sure to disable them all temporarily so that we can be sure it is a KeePass problem and not a plugin problem.