W/O being able to see what exactly is going on, first I'd try some DIF Wallpaper removal. Read the instructions very carefully and follow them to the 'T'. Don't rush. You'll need a Paper Tiger, a sponge, and a bucket of very hot water with gloves to do this job. If the paper is vinyl or was painted in the past, the job may not be so easy. BUT, my point is, you should exhaust all the methods to remove the paper first before you joint compound up the wall. (Getting to the original base is best, of course.) You can use a 3" spackle knife to scrape but be careful not to dig into the wall. And when you use the Tiger, you only need to perforate the wallpaper; NOT the drywall underneath. And when you're finished, wash the wall with a clean mix of DIF. You can find DIF in any Wallpaper store or at any Home Center.