mouseprobzz

hello everbody,
when i play ET , i use mouse2 to shoot with smg because i often use my mousewheel to toggle the fov, so if you bind +attack on mouse2 you can use both at the same time without lifting your finger of the action button. now i also use mouse1 for shooting with pistol.. but since a few days my mouse2 is acting weird. when i click it , my weapon only starts shooting after a few seconds... and when i prime a nade, my player drops the nade after the second click. it's incredibly annoying and i would like to know if any of you knows whats up with it? when i shoot with mouse1 for both smg and pistol there no prob, only for mouse2, but as i explained earlier, i need mouse2 for the toggle. any help?