Clicking the Commit Changes option in the Admin webapp resaves all the context XML files in \conf\ with the current in-memory state. This process does not take account of the effect of antiResourceLocking (which is turned on in the META-INF\context.xml file). If a webapp with this option turned on is running when the Commit Changes button is pressed, the antiResourceLocking-modified docBase will be written out to disk. The problem is that should you then stop Tomcat (with the webapp still running), on startup it will read in the docBase and get very confused because it can't find the webapp in the \temp\ folder (which of course got deleted on shutdown cos it was only temporary). Net result is you can't access the webapp and have to undeploy and redeploy.
Never assign a bug directly to someone.
Fixed.