Jikes, yikes!!!

One of my students copied TrackFire and added a few lines of code to it.

Trackfire compiles to completion while his revised version freezes the compiler on a blank window. The window is modal. You can't do anything else except shutdown robocode.  I've tried to figure out what part of his code causes the compiler to freeze.  So far, no luck.

However, it seems the compiler does go to completion.  We ran a battle after the freeze up and saw the changes he made.

So, why is jikes not returning from what seems to be a successful compile?