I am writing a basic Java application with a Swing front-end. Basically it loads some data from a Derby database via Apache Cayenne and then displays it in a JTable. I'm doing my development in Eclipse and I don't think it's important but I'm using Maven for dependencies. Now this works fine when I run using Debug but it seems to hang the display thread when I use the Run button. I've done a thread dump and I'm not 100% certain but everything looks good. I used Java VisualVM and the threads look fine there as well. Strangely it seems to work intermittently. It's pretty consistent though and easy to reproduce. If anyone has any ideas, I'm all out of them.