Ashley the problem is the collision is getting stuck with the edges of the solid tiles. Gravity should cause any collisions to have friction, but not make you clip to another object. For example, if I have a diagonally blocked sprite (something that is not blocked completely on the same X value all the way from top to bottom), it will get stuck on it. The greater the difference of the angle of the block, the more it will clip.
I've read you say to use movement with a 32x32 square, but it seems like a bug to me. Developers have to do a hack around it. I personally do not want to design my game around a 32x32 block square. It defeats the purpose of collisions in the first place.