Preview of .psd file(s)

when I preview (hover mouse over) any .psd file, dopus shows correctly the small thumbview but dblclick says ".. is invalid or not recognized file format"

system has ACDSee 9 and Photoshop 9 so I can open in either but wondered why dblclick would not show the viewer?

Is it a CMYK image? If so it's this issue: ... light=cmyk