Software error? As usual - undo the Last change that you did just before the error occured
Well I guess there have been no changes (? - never change a running system!!!
), so a software issue should not make PBW refuse to work after running for such a long time. Maybe the database is corrupt or needs a purge? Disk full? Capacity problem - memory? Faulty memory chip?
It might also help to upgrade to the latest Version, but I'm not up to date with Tomcat, known problems and bugfixes. I would probably make a backup of the database, delete it and create it new and fresh, and check if the problem persists. If not, copy the old tables one-by-one until it crashes and if, you have at least located the problem.
I have some time at hands, I can give you any help with mySQL if you need, but I'm no Tomcat expert.