If, from the simulator, you save a non-empty trace and immediately open it
again, it does not want to load the trace.
Example: create a model of one automaton with one location and a transition from
that location to itself. From the simulator take one transition, save the trace
and open the trace again. You get an IO Exception.
Changed description to "Saving does not work", as loading a trace file generated
by verifyta does work.
A fix has been checked into CVS.