Right as no one's come up with an official answer yet I have decided to invent one:
The real reason that it was blocked off, is that someone left the back door to the Haunted Mansion open and one of the pesky poltergeist got out

he then proceeded to possess one of the animatronic from the COP (Which went unnoticed for a quite a while as people were distracted by the new paint job).
so now with a body it progressed to main street, as you know, it wanted a Coffee, some ice cream and a crystal Mickey to add to his collection and started to run amok in the stores. As this happens more that you think, it was phoned through and I have the transcript from the cashier end of that phone call:
"Hi it's Marge over at Crystal Arts, we've got a 1-999, yeah a G-bust. Yes it is Kevin again, I don't know some idiot must have left the door open. Okay well you just deploy the troop and if anyone asked just be vague... No don't say it's a medical emergence as that will send people crazy, next thing you know it's 12 Monkeys all over the forums".
"Just go get Madame Leota, I don't know, just put her in a shopping bag it'll be fine, okay see you in 10".
And with that Madame Leota was brought to the store performed the exorcism and banished the spirit back to the house, the CMs put the animitronic back, on the COP, before anyone on the ride woke up.
So in the end order was restored, but they still never found out what was in the shed, dun, dun, darrrrrr.........