Architectural Desktop Incompatibility

When I add to drawings created with AEC objects and send them out I am told they crash Autocad. I have done audits with Autocad and they give an error message saying duplicate handles. I have the Autodesk Object Enabler running and Acad can usually audit a file and fix it, but some of them have fatal errors and only open in Icad. I end up wblocking out my work and they telll me that those files work fine. The problem seems to be WAY more frequent in the last six months or so. (i.e. not necessarily a Bricscad 6 problem. I am running Version 6 Pro.) I believe it is a problem with Architectural desktop - particularly with older versions of it. (ver. 2000) Any ideas?