I usually dont use beta drivers. What I have installed currently is the latest stable release Catalyst 14.4
My keyboard is a shortened one, it doesn't have a numpad so i couldn't try the keystroke you suggested. So all I did was change the DayZ.cfg and entered my resolution 2560x1440 instead of what it was set to by default (640x480)
It worked!
I'm running into some new issues now but this specific problem is now resolved.
Thanks!