Multithreaded external (Win32)?

I have a Max external project which connects to a Wiimote and creates a secondary thread where I attempt to update the acceleration data and output the results to an outlet during each update frame. This seems to generate an access read violation at the following line:

outlet_anything(data->sender->m_outlet[1], gensym("accel"), 3, av);

I implemented a critical section in hopes that it would correct the issue, but it still fails. Does anyone have a working example of a multithreaded Max object? Is multithreading even allowed?

EDIT: Oops, I meant to post this in the Dev forum.