Are you by any chance on Windows XP?
* Adobe Photoshop® Extended 3D features and some GPU-enabled features are not supported on Windows XP.
Please give further details about your machine and OS.
No, I abandoned the Windows platform long ago. I'm using Mac OS X, 64-bit Intel. All my software is up-to-date as of May 10, 2012 and my computer is in complete working order. I have Photoshop CS5.1 Extended on the same computer as part of CS5.5, it works just fine.
I use Photoshop more than any of the other programs in the Suite, although I use a lot of them, and if I can't get this fixed I'll need to switch between CS5.1 Extended and CS6 to get everything done. I've reinstalled Photoshop twice, and both times it shows up as Extended until I launch it activated. I launched it before activating it the second time I installed it, (the first time separate from the suite) and it worked as Extended then. But once I put in my serial number it switches to the regular version every time.
Something's not right...to state the obvious ;-)
Did you order thru the Adobe.com store? Have you tried licensing other apps that are exclusive to the Master Collection (eg. Flash Builder)?
I completely uninstalled the Suite and reinstalled it from scratch. I have Photoshop Extended now.
Thank you all for your help, it seems the answer was so simple, however inconvenient.