So it seems we have found the source of the problem and a temporary solution. Pure Data behaves strangely or crashes because of the ability in OSX 10.8 to use AirPlay as main out. This is automatically selected on Pd startup.

The solution is easy: when starting Pd, switch off your wifi. After Pd is started, you may switch it on again.

I'm mathoglu's friend.. The problem has now changed (strangely enough for both of us). We can now start PD but it freezes when we try to change audio output (it is automatically set to AirPlay). Also, there seems to be a problem with bangs. They get stuck. Any bng object that is triggered stays black and won't throughput bangs more than the first time.

These problems started after upgrading to OSX 10.8.