I think I am going crazy.  SW, she's playing tricks on me again.

I want to change the material of a part.  I go to the tree and RMB on the little material icon.  I do not get a option to "edit material" anymore.  I would swear that is how I used to do it.  I even did a quick search and the few sites I read said to do it that way.  My co-worker gets the option on his system.  Anyone have any ideas why I can't change the material?  Did I accidentally turn off some option?