First, is the phantom power on ?
Second, how many device do you have plugged into your power socket ? (the one from your house) Do you use power strip ?
Third where you at ? (Depending on which country you're in the maximum power can variate. Here, in Belgium, I can have 220V)
Answer and we'll see where it comes from. (Def from you computer, but that means, you've something plugged in and it's too much)