This could be caused by a couple of things, caused by either poor hanging or finishing work. We can get more specific if you can tell us a bit more about the problem. Is it just the tape that's lifting from the board, or is the board popping? Press lightly at the seams where the problem is occurring and see if the board will push in a bit. Also is this going on all over the house or just in certain areas, say like the bath?
Post back with a bit more info and we'll be glad to help you out.
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