I'm having some problems to get it to run with Java 1.5 in both, Firebird and IE. It loads fine, it initializes everything and after doing the combined-vs-splitbuffer-test, it's sitting there displaying the Java 1.5 applet logo and nothing happens. However, it seems to do something in the background, because it consumes 50% of CPU power on my hyperthreading machine (i.e. one virtual cpu). If i reload the page, the actual game screen appears and i can play, but i'm at 100% CPU then, which means that the former instance of the game is still running in the background.
It worked fine on a 1.4.2 machine last weekend.