Andy I think I would have been on the phone to Microsoft product support well before I hit 3 days trying to resolve this issue. This seems to be deep internals stuff and hunting and pecking on a forum likely won't be the thing you need (and certainly hasn't to this point). Add in the fact that relatively few people are on SQL 2008 at this point so we don't have a large body of knowledge/experience to draw on and you again get pointed to MS. 🙂

Best of luck with it. Perhaps you have stumbled onto another bug?