As Noel suggested on the PS forum where you first posted the question, uninstall and reinstall PS CC 2014. This works for most people, and many have had this issue.
Many thanks for your response
I have a new problem. When I try to activate the "Uninstall Photoshop" icon, I get the message that “Uninstall Adobe Photoshop CC 2014” is used by OS X and can’t be opened.
I have raised a new query, I'm sure people will be as helpful and forthcoming as you have been.
Same problem here. I uninstalled Photoshop CS5 and reinstalled. No change. I also tried dumping PS preferences
It opens the Photoshop application with all the menus/windows, but it never opens the actual image I chose to work on.
I'm on a Mac, using OS X Yosemite, 10.10.1 Lightroom is version 5.7 Photoshop is CS5, version 12.0.4
FWIW, I also can't automate>Photomerge ... . Makes me think Photoshop, not Lightroom, is all wacky.
Same problem as michele