Sometimes yes. Also all my torps and mines, especially quantums, occassionally activate, hit the cooldown and do nothing. It's killed me a few times when i've played chicken with a shield facing down cause High Yield had just cooled and then completely failed to fire.
Yes. It's a small flaw in the engine of the game. Champions Online has it as well. If you've played both, you would know what is going on and would be compensating for it by now. Sometimes your button presses on your keyboard register but the engine itself thinks something else for some odd reason or other.
It still has yet to be fixed. Meanwhile, bug it... post it in the Bug forums... complain about it... and maybe one day we might have responsive controls.
Oh, and to "fix" the problem, just hit the button again right afterwards. It's a pain sometimes, but it happens.
If you wish to test this out really well, go to the ground and have two different weapons equipped. Switch (Z) between them about 10 times or so. See how many times you press the Z key compared to how many times you actually switch weapons.
I've been seeing this a lot more in the last week or so. Seems to be everything so far, not just specific actions or slots. I've also noticed that my action bar keeps filling up with a random selection of abilities whenever it feels like it.
Its quite irritating to be excited at the prospect of four torpedoes pew pew pew pewing out of the launcher, only to see one lonesome little torpedo making its way to the target becuase High Yield III didn't activate properly.