ARGH! Knob suddenly doesnt work in Live 8???

[B166ER]

So I'm playin around in Impulse, and out of nowhere, the decay knob stop working, and the sample gets stuck like it's on 0.000ms, in other words the sound is a faint click! the orange ring around the knob is now black, and I cant tell what i did to make this happen! The other slots are fine in Impulse, just this one. I even shut the project down and started it again, and the ring started out orange, then went black while i was tweaking another sample. I can turn the knob, and return it to default, but nothing fixes the problem, the ring stays black, and the sample stays a faint click! And for some reason, I cant even get a screen capture to show y'all what i mean! I'm having a fucking moment! I swear I couldn't even pour a glass of Kool-Aid and not have an earthquake happen! help!