I have some PDFs inserted as External Items in my ENERCALC Project Files.  Why are these now misbehaving?

 

It probably has to do with a setting in Adobe Acrobat.  Fortunately the fix is easy.  In Adobe Acrobat Reader X, go to Edit > Preferences.  In the General category, deselect the option to "Enable Protected Mode at startup".  This should resolve the issue, and PDFs as External Items should now behave as expected.