Sigh. Nearly the same problem, probably a different cause.
Using a legacy version of Mac OS (umm. 4.something?) which could run the default client (relatively) happily in W7.
Downloaded it so have autohaven on the desktop as per usual, got message about do I want to trust this certificate as per usual, clicked trust as per usual then it quit.
Possibly this is just the universe telling me that NO REALLY IT IS BEDTIME, so now I will go to sleep.
ok I figured it out, was just java issues, uninstalling the old java stuff messed up my pc for some reason, but I simply uninstalled all java and reinstalled it. Working fine now.