When encountering server-side errors in a Japanese locale (ja_JP) JVM, Tomcat returns strings of question marks instead of sensible error messages. A Japanese explanation, screen-shot, and work-around exist here: http://www.fk.urban.ne.jp/home/kishida/kouza/tomerr.html; I am not certain why this has not been submitted as a bug. This still exists in 5.0.27. Thanks. Yoroshiku onegaiitashimasu.
*** This bug has been marked as a duplicate of 28875 ***