Go to C:\Users\YourUsername\Documents\My Games\UnrealEngine3\ShooterGame\Config
Open ShooterUI.ini
Find the command:
NativeHUDResolution=(X=1280, Y=720)
replace it with:
NativeHUDResolution=(X=0, Y=0)
It will disable your ingame Interface (ammo, minimap, killfeed)
I’m having the problem since 2month and this was the final fix, hopefully Splashdamage will fix it.