I'm affraid you may need to go to an earlier driver set. I've been checking around and I'm affraid it may be a bug in the newer Catalysts, with no workaround. If I'm understanding the bug correctly, it works for Mem because he had used BNC's with a prior set, and "some" setting was kept in the registry, that won't be available if you start with a later set and upgrade...thats why your apparently won't work with the same combination of Driver and CP.
Normally, I would have caught it myself, but haven't used my BNC cables for the last couple sets due to some swiching around some PC's and components at my place and just realized I'm using VGA on my Monitor.
If I hear anything else, I'll post it ASAP. Make sure you report this to the Catalyst team (link in my sig)