#23 NullPointerException on Matcher.find()

[Shin]

Does anybody got NullPointerException at Matcher.find() ?
I am not sure what were the parameters and the pattern string because it was not running as debug mode.
After once it got this Exception, the same exception happened every time Matcher.find() was called.
Thank you for your help.

java.lang.NullPointerException
at jregex/Matcher.findBack(bytecode:-1245676532)
at jregex/Matcher.search(bytecode:3017)
at jregex/Matcher.find(bytecode:13)