Starting in AutoCAD Architecture 2010 I noticed that in some of my drawing files, the Zoom command or Save command would set my drawings to perspective and turn on the background. This behavior did not occur in most of my files so I didn't spend much time worrying about it.

Now in AutoCAD Architecture 2011 this display bug thrives.  In a recent file just the Pan action on the wheel mouse causes my display to go to perspective with the background on.  What a freak'n pain.

If you haven't experienced this bug, what happens is that you are in a 2D Top View, for example, and then execute a Zoom, Pan or Save command which triggers the View to go to perspective.  When this happens, the UCS Icon changes to the 3D shaded version and the background changes to gray.

There really isn't a solution until Autodesk fixes this bug but there are things you can do to make it less intrusive.  The culprit, as far as I can track it down, is the "Skystatus" setting which stores three options: 0 = Sky Off, 1 = Sky Background and 3 = Sky Background and Illumination.  If you simply set Skystatus to zero you may find that nothing changes; in fact, in some files I set it to zero but it just resets to the previous value.  When this value gets stuck, I have found that you can set it to 1 or 2 and then come back and set it to 0.

For best results, you need to go to a Perspective View and then set the Skystatus to 0 in order to restore normal display functionality in your drawing file.

In the illustration to the right I show a trick you may find useful: create a Named View for your perspective work using the Background Override set to "Sun and Sky" and then create another Named View for standard work.  When you switch between these two Named Views, you should find that the display works as expected.

Hopefully this short article demystifies a display anomaly in AutoCAD Architecture that can easily drive you nuts. 

Update (2-18-12):

One of our readers reported that he found using lisp to toggle the "Skystatus" setting kept the setting so it didn't revert after opening a drawing file again.  Here's what he uses"

(setvar "SKYSTATUS" 1)

(setvar "SKYSTATUS" 0)