The whole story:
The JBoss Maven repository recently changed one of their artifacts so
it redirects to a newer version of the artifact. This was only just
now discovered. This "new" artifact was compiled using Java 5, so
it's likely that it would not work on Java 1.4. By downgrading to the
older version, PSI Probe 2.0.1 should work on Java 1.4.
Please let us know if you encounter any trouble. You can do so
through the issue tracker or the discussion group.