I've got an intermittent exception that occurs roughly once every 80
hours, (once per 14 million calls of this routine).

I had the following line throwing on me:
objectResult = m_queue.Dequeue();

I broke up the lines into two:
object o = m_queue.Dequeue();
objectResult = o;

And saw the exception coming from the second line.
I added a retry loop around the assignment to objectResult, and I've
since reproduced the problem once, and the first retry failed again,
the second retry worked.

WTF?

Dual CPU machine w/ HT-enabled, 4 logical processors.
Running the "normal", non-server version of the CLR (bad idea?)

The out parameter exists on the client side like this:
object oResult;
WaitForResult( out oResult );

The out parameter gets passed through 4 functions which delegate to
other functions passing the out along the way. I've reproduced this in
both debug and release mode.

Thanks a ton,
-ken