Alt key acting up

[xDaemianx]

So, I'm playing normally and, at some point I decide to use my spells in my third tab and, therefore, I press a side button next to my left click (=alt) + one button on the side of the mouse (say 4), so my (fourth) spell on my third tab would be cast. The thing is that, then, the game "thinks" that I'm still pressing ALT and if I try to move sideways, left (A button), the game will enter Alliance Chat (alt+a), which brings me to my (other&main) problem: I can't use my spells placed in my first tab because the game still "thinks" I am pressing alt. In other words, the moment I use one of my 3rd tab spells using alt+X (either keyboard or mouse), the game will "keep thinking" I am pressing ALT and I won't be able to use my spells on my first tab (bound to the range of keys from 1 to 0).

I know binding the third tab to a different key would solve that problem but the problem of entering chat modes using alt+a/s/f/... would make this problem persist, at least in terms of movement.