There can be an issue opening DWG file correctly on some workstations with AECOsim Building Designer. In some instances workstations would display the error "[<path/name>.DXF] is not in a recognized file format", Installation, configuration and DWG seed file issues were ruled out during analysis.
After further testing the user found that running Adobe Application Manager on the affected workstations, which had Adobe Creative Suite CS6 and Acrobat XI installed, allowed Bentley applications to open DWG files again. Adobe Application Manager installed Adobe Creative Cloud, we currently assume that some error in the previous Adobe Creative Suite installation was interfering with the functioning of the RealDWG libraries.