Drag rigid body problem

I'm trying to make object dragging like in amnesia or penumbra. I use a script "DragRigidBody.js" and have problem with it. The object begins to jerk if I try to drag it into the wall. I experimented with all the settings of this script, but the result remained the same. I want to achieve the object in a similar situation just a "slide" on the wall.

Maybe I explained bad so I attached video - https://rapidshare.com/files/2292680249/track01.wmv Thank you in advance.