In RTX166 Tiny if all tasks are left waiting for signal simultaneously for more than a couple of minutes, the system crashes (that is, when a signal is finally issued the program jumps to an unpredictable location). I checked that both in simulator and in target hardware. In simulator it can be seen that the problem occurs only after task timers roll over from 0 to 0xFFFF. I've never reported bugs before, so I don't know if the forum is a proper place for that. Anyway, be aware! Regards, Mike.