Problem : After updating to 2.61 from any version of R2, you may get an "Incorrect file structure" error, preventing the scene from loading, if the scene contained an OSM object.


Solution : 


firstly...BACKUP YOUR SCENE !!!


  1. Update to version 2.69 (or greater)
  2. Rename your scene file, by adding the phrase "DE_RECOVER"  (e.g. DE_RECOVER myfile.c4d)
  3. Load the file into C4D
  4. Save the scene with the original name (removing the "DE_RECOVER" phrase ), and it will now open without problems.