What version of windows are you running? For some reason, I'm no longer able to (haven't for a couple weeks) paste a screen shot into a new file (or any other) within CS5. I can with other applications though. Photoshop is completely ignoring the windows clipboard it seems.
Edit: I wiped the hard drive which kills all temporary files and my the paste into photoshop is now working. Something must have been full up. Still don't know why you cannot use the key strokes you say you've always used though.
Last edited by JeffJS; 09-05-2011 at 01:34 PM.