All tools are randomly EXTREMELY touchy. I’ve tried editing all of the settings and resetting the brushes and restarting blender. It only happens in this .blend (which I’m not able to upload…) It also happens with 2.56.
Try appending the object into a new blend in case the file is corrupt. (or append the mesh, in case the object itself is corrupt…though not sure how that would happen :eyebrowlift2: )