So lately when I used 'prt scrn' button (mapped to Capture Region command), it appears unresponsive; when used in succession. So the first time it will appear to work. then I may hit esc to cancel the command. and until i using the 'refresh' command by going to the quick menu via right clicking on my open desktop, Greenshot's hotkey command won't work again. it gets 'stuck.' and then only seems to work again after i refresh my desktop.
windows 7 64 bit
Intel i5-2500k 3.30 ghz, 4 cores
Geforce GTX 750 Ti, 4GB memory
I'm not sure what this could be, but I wonder if by any chance you are running elevated (admin) processes. For insurance if you run the registry editor, which needs elevation, the hotkeys won't work anymore if that window had focus.