I've never seen this problem. Has there been any signs of bugs? Aphids will cause new growth on plants to wilt (bend over) and die.
Are you familiar with aphids?
It could also be a nutrient defiency. Maybe you could look up your county extension office for advice or at least refer you to someone with the answers.
Sorry I wasn't much help. Just noticed that you hadn't received any answers and I didn't want you to become discouraged.
Let me know what you find out. I may need the info myself someday
Are you saying the stem that holds the cluster of flowers wilted and died?
or the stem that holds each flower bent over and died?
if its the stem that holds each flower that's normal the flower wilts before the tomato's form on the ends.