Novell Support TID: SLED: Firefox scrolling, middle mouse button, like windows
Scrolling in Firefox does not behave like it does in Windows with the middle mouse button.
Linux will try to paste the top most thing in your clipboard when you click your middle mouse button. When you are in Firefox and you do this, Firefox will try to open what you pasted as a URL.
If you would like to get rid of this functionality just for the Firefox browser check out this new TID from Novell Support for instructions.