Your file seems quite buggy - you could try starting with a new empty max scene, and then importing in your objects in by going File > Import > Merge.
Make sure that your material paths are correct, everything - your max file and materials - are in the same folder that you are exporting to, and you are following the correct naming conventions - no spaces or symbols including: -, only underscores: _
It is also really important that you are always saving different versions of your max files, v01, v02 etc, in case one becomes buggy / corrupt.