[Sawtooth G4]

I'm attemping to patch some of the memory leaks in my app, but when I launch it via MallocDebug, it instantly crashes, with the error:
....accessed memory at 0x7c0802ae illegally.

I tried changing all sorts of code to get it to work, and then I got the bright idea to try a differnt app. Everything I tried (including Clock and Calculator) exited with the exact same error message. Changing the 'clear freed memory' option has no effect. Dec dev tools, 10.1.2, sawtooth 450 w 768 ram

What the hell is going on?

Thanks