How do I sand paint runs off of drywall? Should I use a power sander?

I am remodeling my daughters room. The previous owners didn't sand the drywall mud properly, they just painted over it. When they painted they left paint runs EVERYWHERE. Now I want to repaint the room but I want to sand the walls properly. Is it overkill to use a power sander?How do I sand paint runs off of drywall? Should I use a power sander?
I would try a small hand vibrating sander with 220 grit, if that don't work try regular sand paper used for finish sanding, it is coarse and you will probably have to re mud the dry wall, chances are you will get a better finish coat since the previous owners done such a lousy job....good luck.How do I sand paint runs off of drywall? Should I use a power sander?
I would consider using a flat cutter or sharpened putty knife (anything with a nice, straight, sharp edge). Rather than sand the runs down, you could cut then flush with the wall surface. No dust, and much quicker, not to mention more efficient.