Can you upload the console output of a bad session to e.g. pastebin and post the url? I see there's a trial version at http://www.renderpal.com/d_renderpal.php which might be helpful... is it possible to reproduce the problem using just the free trial, and no other software? How many renderers does it take to produce the hang? (Worst case, logs from wireshark showing the hang might be useful.)
