If it's the texture that is the problem, stop sanding and spread a coat or two of mud on as was suggested. Do it in two layers if the texture is really rough and try to get it on as smooth as possible so you won't spend a great deal of effort trying to get it flat.
If it's only the purple color with wood grain (what WERE they thinking?) just use a fluffy roller, 3/8 to a 1/2 an inch thick, to paint one coat of Bullseye One Two Three over the offending color. It dries in a half hour. Paint over with whatever color you want.
Joe(Alway opt for the least amount of dust)Nation