Hi !
We can say it, Led Zeppelin was an awesome live band .. most of the time .. but sometimes thing just doesn't work right. It can be interesting to see some fail moments they did. And sorry if I make mistake I'm french
Well it wasn't Led zeppelin but for Robert Plant, I think of the Live AID in 1985 when he totally stop Page in his solo on Stairway to Heaven, maybe it's the fault of one of the drummer who start the fast beat but Plant heard this repeated lick thousands of time so he knew it's wasn't the end of the solo.
Link to the video :
https://youtu.be/CBk-iRihSUg?t=8m25s