This was caused by the tomcat cache being out of sync. On SuSE, tomcat keeps a cache in /srv/www/tomcat5/base/work/Catalina. Stopping tomcat, removing Catallina (and everything below it) and restarting tomcat fixed the problem.
We picked this up by noticing that the title bar reflected 1.4.7 when we were editing the queue rather than 1.5.0 at other times.
Tony