or this:
. Make a copy of the file and place it on the desktop of the boot drive.
2. Try opening up the document from within Photoshop; As a Smart Object
(If it opens, it will open flattened and not layered, don't panic)
3. Close the file (If the next step doesn't work, you can always go back to step two and salvage a composite version)
4. This is the key -- Now go to the Open Recent flyout list and choose the document again.