Photoshop not recognizing jpeg files

Hi Adobe Folks, 

Has anyone had problems with Photoshop, following an upgrade, not recognizing jpeg files? It still opens psd files, as usual. PhotoMechanic, iPhoto and other non Adobe related programs open the jpegs as usual. I get an Adobe Photposhop Window with "Could not complete your request because the file was not found." This seems like a simple fix. Many thanks in advance.