The first meltdown occurred when we first bought the potty. See this post. The second one occurred today. Here are the details...
Two days ago Morgan pooped in her little potty for the first time. Yay! Grandma and Grandpa B were here. After lunch I changed Morgan's diaper for her nap. Right away she grabbed another diaper, said "poopy" and ran into the bathroom. I ran in there after her. Took off the diaper and sat her down. I read her a story and sure enough, she pooped! She stood up, looked in the potty and said "poopy"! We clapped and cheered for her. She was so proud of herself!
Today after lunch I suspected another poop was eminent...so I took her in the bathroom and sat her down. Again, we read a book and she pooped!! But...this time she peed a little and set of the sensor in the potty chair, so music started playing (remember how much she liked hearing the music?). No, this time she stood up and starting a combination of crying and screaming. She ran into the living room and I chased after her in fear of her sitting on the carpet since I had no time to wipe her. So I'm trying to wrestle this screaming child so I can wipe her butt while telling her she did a good job at the same time! I'm not sure she got it.
So, we'll see if she goes near that potty again. I think I'll be disabling the music feature. Too much trauma.