This phenomenon receives its name from the premise of a pet "talking" parrot who is suddenly silent when guests are invited to see it "talk." "I swear!," says the owner, "He says all kinds of stuff! He says 'hello', he says our names! Really! I don't know why he won't do it now...." while the guests nod and say, "Suuure, he talks. We totally believe you."
You "Every time I try to load this page I get a weird error message. I restarted and everything. Come in here and look at this."
IT Employee: "OK, show me what it's doing."
You: Repeat action that has resulted in a error 17 times in a row. Page now loads no problem. "I swear, it was giving me an error every single time before you were standing here. Talking Parrot Phenomenon, right there."
IT Employee: Gives you skeptical eye.