Seems to be a wierd problem. Started playing again, and it seemed to work on my one character, but not another
*edit*
Ok, normally when you press both mouse buttons down (left + right) you walk, until you release. When I press both mouse buttons, nothing happens.
If I'm autorunning, and I click and hold left mouse to try to swivel the camera around, my character acctually runs slower.
It's very wierd, and really starting to annoy me that I can't figure it out.