Photoshop CS6 Extended starts instead of Photoshop CS6

I have a licenced copy of Photoshop CS6 in my Windows 7 computer. Today, when I start CS6, CS6 Extended starts instead, in trial mode. Control Panel Install/deinstall shows I have CS6 installed. I don't want to deinstall because I can't get into CS6 to deactivate it. Maybe I have to wipe the PC and return to a recent full backup, but is this my only alternative?