I am at a workplace that uses both AutoCAD LT and DraftSight, and I am running into interoperability problems between the two.  It seems that if a file is ever saved in DraftSight, that all objects in that file are converted to mixed AEC objects. 

When I open the DWG in AutoCAD, I get this error:

     "The drawing you have opened or referenced contains custom objects created by an unavailable ObjectARX application.  You do not need the original application to display proxy representations of objects that were saved in the drawing, However, many manufacturers, including Autodesk, provide object enablers that also allow you to edit these custom objects..."

I can get rid of this stupid popup by configuring AutoCAD PROXYNOTICE to a value of 0.

But, when I go to paste a copied object in AutoCAD, I get this error - every time.

     "This application has detected a mixed version of AEC objects participating in this operation.

Newer AEC objects will be disallowed from particpating in this operation."

Then, after I click ok,  it pastes the object anyway.

Is there some sort of percieved advantage to making DraftSight unusable with AutoCAD?  AutoCAD won't even get rid of the AEC objects, because, the -EXPORTTOAUTOCAD command gives this error message, "Command not allowed because drawing contains objects from a newer version of this application."  Why would DraftSight even put forth the effort to convert every single line, arc, and circle to AEC objects?

I am currently using AutoCAD LT 2009, and DraftSight V1R5.

This is a ridiculous problem that should never have happened, how do I get rid of it?  Can I configure DraftSight to never use AEC, and to convert everything back to simple objects (lines, arcs, text, etc.)?

Thanks