In the TimedLock class:

The factory method TimedLock Lock(Object o)
calls the TimedLock Lock(Object o, TimeSpan timeout) method
which passes 0 milliseconds to the TimedLock Lock(Object o, Int32 milliseconds) method.

This was causing a LockTimeoutException to be thrown (using the implementation from this post http://davybrion.com/blog/2009/07/protecting-your-application-from-remote-problems/)

The problem was fixed by changing timeout.Milliseconds to Convert.ToInt32(timeout.TotalMilliseconds) inside the TimedLock Lock(Object o, TimeSpan timeout) method.

public static TimedLock Lock(Object o, TimeSpan timeout)
{
return Lock(o, Convert.ToInt32(timeout.TotalMilliseconds));
}

I think I understand, but this is one of those cases where a picture is worth 1K words.