Oh dear, I don't know. There are three scenarios:
a) when I wake the screen I can't do anything else and the Reliable Alarms clock is
still at the top of the screen, then the clock goes after a few seconds
and the phone starts working again;
b) the phone doesn't respond after waking the screen, and then a pop up with something like 'Tasker is not responding would you like to wait?' appears with two options;
c) something has happened while I wasn't using the phone. I have an icon displayed in a scene, this icon tells me what set of sound/display settings is selected. If that icon is not there it seems to mean that one of the above has happened.
I probably don't know what 'crash' means officially, maybe that's the wrong word, but something is happening that shouldn't happen.