When starting the latest Phex 3.0.2.100 on a computer with java 5 update 8, I get a "class name error" or something like that in a terminal (and otherwise nothing, no program start at all). Sorry I can't easily provide the exact error since I updated to Java 6 and the problem was solved. This occurred on Mac OSX and windows.

EDIT: I rebuilt with 1.5, I couldn't figure out how to force 1.5 compatibility when building with 1.6