So, I wouldn't normally post something with this little information, but...well, this one is just kind of funny.
I saw this on the website Happyplace.com:
Looking for more information brought very little. I found a contest at the university's museum where participants were supposed to find the "source of a haunting" (the contest even has a Facebook page), but I cannot determine whether the sign is connected to the contest, or something separate. What's more, I can't tell whether this is a joke by the maintenance staff (or a joke by someone pretending to be the maintenance staff) or if the stairwell is really closed because of an alleged haunting.
Commentary: For once, I have very little to say. There are no details, this is more likely to be a joke than to be a sign seriously placed, and it might be related to a contest.
At the same time, the fact that this sign was placed is likely to create at least a few rumors, if none already exist, and therefore is interesting as a potential seed for folklore. But, really, that's all that I have to say.