Under what circumstances do you lay day a set preflop in a cash game?
Here was the scenario I had:

2/5 no limit
full table
on the button

Utg opens for 20, middle positon calls, I call with a 55, BB calls.
Flop comes 5 9 10 rainbow
BB bets out 20, utg folds, middle positon calls, I raise to 60(I have $900), BB folds, middle pos player reraises to $200 (he has $1400) note: There was an unlimited buyin with a relatively tame game before this guy came to the table. He bought in for $2000. Most of the players bought in for about $500. He was involved in about 2 out of 3 pots playing aggressively for the hour he was playing at the table.
I thought I had two choices fold or allin. I didn't even consider flat calling. I thought about it for a minute and pushed it in. He had a set of nines. I lost.
What is your thoughts.

1. You cannot fold a set pre-flop
2. That board is not scary for a set, but requires protecting against QJ.
3. Never give your opponent credit for an over-set.
4. folding is not an option here, push.

tough break but what LJ said.

a preflop set is quote a rarity. i only saw it once and i think I was high. anyway, I don't think you can lay that down. Just bad luck