Problem: Some tools in ArcMap are disabled when setting data frame to use a fixed scale or extent
The pan and/or zoom tools have become disabled in the Tools bar.
If the data frame is set to fixed scale, the zoom tools become disabled as their use would change the scale of the data frame. The pan tool, however, remains enabled. If the data frame is set to fixed extent, both the zoom tools and pan tool are disabled. This is by design.
Solution or Workaround
To regain use of the pan and zoom tools, set the extent of the data frame to automatic.