[OT] bugs in JDK regex engine ?

Some of you might be remembering, that I posted an experimental XML
well-formedness checker few days back.

I had been trying to enhance it since last few days, mainly using the
JDK 1.6.0 regex facilities.

But few of the things documented in the JDK 1.6.0 regex documentation
don't work as defined.

Has anybody who has done serious regex programming with JDK 1.6.0
encountered some bugs?

If somebody can help me with JDK regex's, I can post few examples
which don't work for me ...

-- 
Regards,
Mukul Gandhi