Walls and Ceilings - Removing Cork from Wallboard

We have a bedroom wall that was covered with a thin layer of cork, probably 15 years ago. At one time there must have been a leak at a window, because now there is a dark stain over part of the cork, probably from whatever was used to stick the cork to the wallboard. We want to either get the cork off the wall or cover it with something so the cork and the stain can't be seen. I tried to pull the cork off, but it won't come without tearing the wallboard paper. Can we paint it or wallpaper over the cork? Or is there some way to loosen the adhesive so we can remove the cork and adhesive and then paint or paper the wall. Any suggestions greatly appreciated.

My suggestion to your cork problemm is to first remove the window trim and carefully fill the cavite between the window and rough frame with foam insulation (careful not to overfill 1/3 at the most as this stuff really expands and can get into places you dont want and move things when expanding.Low expanding foam is sometimes available.)Next simply drywall directly over the cork.the layer of cork will probably help to deaden sound, a bonus if you work shifts.Window and door casings can be extended with very pleasing results by imaginative use of molding combinations.