DNS bug in SBS 2008

It seems that there is yet another bug in SBS 2008. When using root hints in DNS, the service stops working after a while (1-2 days) and you have to flush the cache to get it going again. In services it states that it is started and running but it cannot make any DNS lookups. However if you use forwarders there is no problem… And again it is not appearing on all installations so I have not found a trend yet.