10.3.9 on this machine. never saw this problem before - it has happened every few hours (8-10 times now) after upgrade to 2.1 (3338) after autoupdate prompt.
consultation in #colloquy suggested it might be scrollback setting (was at 1000) and so i lowered it to 500. since then, i've seen three beachballs and i had to force quit each time to get back in.
had 4-5 rooms open each time. usually no more than a couple messages in the scrollback(s) before i see that the app has frozen. not sure if it has ever frozen with *no* messages in scrollback for all the rooms.
i have no crash logs in CrashReporter? as the app is freezing, not actually crashing.