I have seen errors like this, too, but don't understand them in this instance.
The difficulty is that the next-to-last line of the program is the one that prints out the
"++ #Flops..." message. Then the last line is
"exit(0)". Not much room in there for an error. I'm guessing that something funny is happening during program rundown, but don't have any way of diagnosing what happened earlier to cause that.
Are you running on a Linux machine, or what? Are you using the "-stim_times" option?