Leosghost - 12:20 am on Feb 19, 2013 (gmt 0)

Ok ..so you are looking at 3 which I know first hand that work ( there may be others / more, but these are the ones that I know defeat printscreen )..

Copysafe..
or locklizard..
or..ebookeditpro..( I run an old version of the ebookeditpro..works well for CHM type ebooks..stops print screen on all win versions..but I do not know if it still is available..their site has said "update in progress" forever.. ) ..I have heard that there is no "support" now..and that some buyers in the last two or three years have had problems either reaching "support" or receiving product paid for..YMMV

I also run some copysafe products..they work well ( they use their own browser for "secure PDFs"..the PDF reader browser is free and can be auto bundled with your secure PDFs made using the paid for product ) ..This would be my suggestion ..

Locklizard is waaay more money..I've used it ..works.. ..may well be overkill / overspend for what you need though..

I have no association with any of them..

HTH :)