Clipping on stairs next to Portal to Piety

http://imgur.com/hH04imb

This is on the left set of stairs. The portal to Piety is a little to the north. I click to have my character go down the stairs, and then as my character starts to go down the stairs I click on the area northeast of the staircase. My character will clip through that little 90 degree corner and the screen will flicker because the character is rapidly going up and down.