When SLI is disabled and all four monitors are active (as shown in the pic above), do all four monitors work perfectly?
From reading posts in a few forums, it seems that it has something to do with the order of installation of the hardware/software and the order of enabling.
So, perhaps you can use a little patience and try various ordering. As Nvidia says it works, it certainly should, at least ideally. But this is no guarantee as, you know, computers have a mind of their own. Sometimes it works (for some people) and sometimes it just does not work for no apparent reason.
For example, below is a guy with GTX470 SLI (driving three monitors) and a GT430 (driving a 4th monitor/TV). Check out his order in post #9. Mimic that to see if it works for you.
And, you may also try to post your problem to WideScreenGamingForum where there is a section for multi-monitor gaming. I suppose the people there have more experience with multi-monitor setup.
Edited by windfire - 3/3/12 at 6:56pm