I was playing the first (intro) mission to check out the three smoke plumes.
Shortly after a particular cut-scene with a famous cameo, I headed towards the third plume.
I CQB'd the first two guys in my way, then headshot the next two guys.
Right after that, all my controller buttons locked up.
I could still walk around and look around (using the R and L sticks), but none of the buttons worked except for the select and start button.
I had to log out of the game and log back in so that the buttons would work again.
It started me right after the cut-scene - and I was able to kill the next four enemies exactly like before.
This time, the buttons didn't lock up, so I'm assuming just a glitch.
Hence, reporting it here.
Thanks