My client seems to crash when I've spent too long on a boss level (every 20 minutes of Vanaduke). (Windows 7, Java 6, fully updated.) The hs_err_pid log file mentions atioglxx.dll, and I seem to remember other people with ATI graphics cards complaining about random crashes.
On a related note, can something be done to more gracefully handle disconnects so that they aren't unavoidable deaths? The idea of having to pay real money because the game crashes is quite...distasteful, to say the least.
What is your video card? its common knowledge that ATI doesn't play well with this and a handful of other lwjgl games.