Installed 6007 this morning on MSSQL build (6006) which had been running successfully for several days. Within minutes of coming back up under 6007 all connection to SD was lost. Could not even connect from localhost!
Uninstall of 6007 is impossible as any attempt to uninstall says the option is not implemented (nor does it appear to have been in any of the patches we have on there).
Have reinstalled 6006 on another server (which I was doing anyway) and restored successfully. So everything is hunky dory.
Will teach me to test future patches better or just wait for the messages to appear on here.