Yes, as I suspected, it was a problem with the .ini file. For some reason, the value was set to an extremely high value:
waiting_msg_delay = 1e+48
I suspect it might be a bug in the Settings dialog, but if you set it to the default value:
waiting_msg_delay = 10.0
It will work. We also added an extra check to be sure an unreasonably high value would be capped to a more sensible maximum, preventing the error. It's already on Live Update now.