Layer Properties Manager - Big Red X. AutoCAD Civil 3D 2012

Occasionally when I open the Layer Properties Manager dialog box everything that should be there is gone and for no apparent reason there's a big red "X" there instead. Closing AutoCAD (after saving my drawing, of course) and reopening AutoCAD usually restores everything to normal.

I'm just curious if anyone else is experiencing this odd behavior.

I've been using Civil 3D 2012 for a few months now and haven't encountered that yet. Are there any precursor steps that causes it to occur or is it totally random?

It normally occurs after I've been in a drawing session for some time. It's never occured immediately after opening an existing drawing or beginning a fresh one.

Are you running any LISP or Add-on programs?

I'm not running any programs or lisp routines that didn't come with C3D. Our company has an Autodesk subscription and I have an on going dialog with one of their technicians. I presume that the Properties Layer Manager "red X" issue will be resolved eventually along with several other recurring issues and I'll post any remedies.