go to your debugger settings once you've launched the debugging.  Make
sure that you have turned off the break on exceptions.  As I recall it
Java throws those exceptions as a normal runtime and that is what is
happening.

It could also be that the working directory is not right and it isn't
finding the class,  there is a setting in the IDE to set the current
working directory,  you can try that too.  

If those don't work let me know more... You might want to post this in
codewarrior.java newsgroup.

Ron