I had the same problem, both were when I stoped Clasic from starting up. When I tried to induce it, go figure, it didn't panic. Everything in Aqua stops, and our good friend BSD comes though.
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Panic (CPU 0); lockmgr: draining against myself
backtrace
Debugger(panic)
Waiting for remote debugger connection
Options Type
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Continue c
Reboot r
continuing...
panic we are haning here
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I messing around with Red Hat a couple timems on my PC, and never seen anything like this before, of course, I don't know that much Linux/BSD/Unix yet anyways.