ALL logs are the unheard screams of your systems, the perverbial grimacing "Ouch!". Instead of going to the code, or the GUI... When there is a problem go to the logs to see what ails your system.
If you've ever gotten so wound up in a problem that you totally miss the easy stuff? Sometimes the "easy stuff" isn’t all that easy. For example why on earth does Tomcat log to catalina.log files anyways?