Further research has determined, oddly enough, that a simple swapping of ports resolves this issue. It did not work last night, however this evening it has worked. It should also be noted that this afternoon I replaced my drivers *again*, and only minutes ago swapped ports. Upon swapping ports both monitors are functioning properly. So while the drivers may be at fault, I am clueless as to where the fault lays and how to recreate said issue. Possibly by uninstalling the nVidia driver, recreation of the problem can occur. Which does seem likely as Windows by itself, without the nVidia drivers would not recognise the 2nd monitor. The question then becomes, is the issue based in the WDDM drivers as installed upon installation or some fault elsewhere.
This new data is making me believe that the issue lays outside the Display drivers as supplied by nVidia or Microsoft (WDDM 1.0). Instead placing the problem with a fault in the plug-n-play system or with the monitor detection system inside the Screen Resolution application. What is interesting is the lack of the audible tones associated with plug-n-play when plugging a monitor into the bottom port. Although, plugging a monitor into the upper port always results in the plug-n-play audibles.
Research on the official Windows 7 TechNet forums resulted in this thread (http://social.technet.microsoft.com...e/thread/273001d1-68c8-4112-91d1-675d9d94d4f4). The OP states simply that the nVidia driver version 181.20 fixed his Dual Monitor issue. It also worked with mine. The OS's are Win 7 x32 and x64 and the issue in question was the second monitor being held in 'sleep' mode.
Good luck all.