If a problem occurs there are three logs you can analyze; the ITP/Server log, the ITP/Document Processor log, and the Watcher log. The Watcher log is the least interesting of the trio. The only reason to view this log is when a ITP/Document Processor log shows that the processor keeps shutting down. The Watcher log can then show the history of that behavior.
For an analysis to be successful it helps when the log level is set to 4. This will ensure that most events will be logged.