A/C-2002 & ADT 3.3 file compatibility

Bricscad 3.1009 is corrupting Archtectural Desktop version 3.3 files created with AutoCad 2002 and ADT 3.3Instead of just "passing through" unaltered the ADT dwg information, Bricscad is causing file corruption that make the original file unuseable and unrecoverable in either Bricscad or AutoCadIs there a solution to avoid this problems? the ADT3.3 files are all coming from our clients so we have no control over them.Thanks jeff