Screenshot problems, prnt screen suddenly messed up

[BOUTTE1]

F-12 still works but taking single shots is slow. I might have to wait 30 seconds or more in between shots and sometimes it causes my game to freeze for varying amounts of time. 

Because of this I've always prefered to use print screen. Been doing this for a couple of years and it's always worked great. Last night it suddenly started malfunctioning for no apparent reason. The pictures are distorted lo res and black and white. Anybody else ever have this problem or have a solution?

 

Any suggestions appreciated.