enV Key Disable?

Every time I hit the period/comma button, my phone acts as if it is the volume down button, and interrupts anything I'm doing at the moment. It puts the period in, but immediately brings up the master volume screen and therefore makes it hard to continue the text or whatever.

Also, at any one time, active or not, the phone will just start acting like I'm pressing the volume down button. I say acting because when the keyguard is on, it will not turn the volume down, it will just light up the screen.

I would have thought it was the volume down button, but with the period button consistently causing the problem, too, I'm thinking it's the O.S.

Tapping or pushing lightly on the volume down button does NOT cause it to go down, so I'm pretty sure it's not the button.