My middle mouse button will no longer rotate the part when held down.  It just quit working.  The mouse is fine.  Its a Logi wireless and i've checked all the settings for what the middle mouse button is supposed to do but I can not get it to rotate the part on screen.  This makes it almost impossible to Mate parts when you can not manipulate to see the surface you want to select.  Anyone out there have any idea why this would quit working and how to fix it?  This is a big PAIN