We're using PM3.2.2 under OS X 10.3.9. Often, asking PM to edit file in Photoshop CS results in Photoshop being opened but not the desired file. In some cases, clicking on the desktop will then result in PS displaying the file, as if it had been opened in the background. In my current case, this workaround doesn't do anything except change focus to the desktop, with Photoshop being hidden.
Often the problem is that the Photoshop installation has been damaged. There is a way to tell if you need to reinstall Photoshop and it goes like this:
Quit Photoshop if it is currently open.
Run Photoshop, wait for it finish loading completely.
Switch back to the Finder by clicking on the Desktop.
Using the Finder, drag and drop an image to the Photoshop icon in the Dock.
If Photoshop does not come forward and open the file, then it has gotten into this non-responsive state that we've seen many times.
Reinstalling Photoshop seems to cure this problem and make it respond again.
HTH,
-Kirk