I know Karl,
I use to think that maybe I was close to my memory limit and the activity monitor put it over the edge. Now with the 64-bit app, I'm not close but I still am seeing a pattern here. Just can't replicate (at this point) on a consistent basis. I thought that maybe the approach that your team is using to access memory may be in conflict with the monitor. Not sure --- that's why I mentioned it.
Of course, Cubase is also in the mix. Not sure if there is something there either considering both use the same security scheme. Take it for what it's worth.........