Hello, I use the Uppaal 4.1.3 snapshot with stopwatches, and I have a situation where the server.exe loops infinitely (during the syntax check) and increase his ram consumption very quickly. The problem appears, I think, since I use difference on clocks with stopwatches. I try to get the bug with a simple automaton, but without success, so I put here a simple automaton of my model where the bug occurs always. You can get it here : http://www.irision.net/uppaal.xml Simon