What instability was there pre Afghan invasion?
Huh? Even if the rest of my list (that you didn't challege) doesn't respresent instability, then what about a 60 year history of assasinations, military coups, overhrown governments, martial law, a civil war and constant warfare?
I don't think it is an arguable point that Pakistan is, and has been during its short history, an unstable nation state.