smp, amd64, and x.org

Since moving to the new X.org on my dual opteron amd64 I seem to be
losing mouse events.   Symptom is a failure of the window the mouse
is in to grab focus.   Moving the mouse out of the window and back
in usually gets the problem resolved.

Problem is more likely to happen when moving between windows close
together with a small gap of root window between them.   What's
interesting about this is that the problem does NOT happen when
booting a generic kernel, only when booting MP.

Problem occurs with both ps2 mouse and usb mouse.  Problem never
occured with the older X.

Any hints on where to look?  Matthieu doesn't see anything obvious
in the X changes.

// marc