Trouble with mouse in full screen mode

[GpB311 236]

I havent played anything on steam in a few days, so I hop on tonight and for some reason Im having trouble with my mouse.  When any of my steam games are in full screen mode, including DayZ and ARMA 2 and 3, I cant select anything with my mouse.  It works fine in window mode, but for some reason it only highlights what I point it at, but wont select it in fullscreen.

Its always worked before, its funtioning pefectly otherwise, and the batteries are new.  I havent changed anything with my computer except the icon sizes on the desktop, but after switching those back, its still not working.  I double checked my resolution and its where its supposed to be. Restaring didnt help either. As far as general stuff with the computer, the mouse is working perfectly.

Intel 4670k

msi z87 GD65 gaming mobo

gtx660

8 gigs 1600mhz ram

21" monitor at 1600 x 1200

[Trigger Hippy 176]

Run the game in the same resolution as your desktop?

[GpB311 236]

As far as I can tell, everything is set to the screens native resolution, 1600 x 1200, the same as it's always been.