Jan, please execute the following at a terminal and advise if the issue is reproducible: synclient MiddleButtonAreaLeft=0 MiddleButtonAreaRight=0 MiddleButtonAreaTop=0
Jan, please execute the following at a terminal and advise if the issue is reproducible: aLeft=0 MiddleButtonAre aRight= 0 MiddleButtonAre aTop=0
synclient MiddleButtonAre