In the same version Media Composer that generated the OMF file, import the OMF file into a new bin in a new project. Confirm that it imports correctly and can be played back correctly. If it cannot playback, go back to the original project and bin in Media Composer, duplicate the Sequence, make a new bin, and drag the duplicated Sequence to the new bin. Now try exporting the duplicated Sequence from the new bin and confirm that it can be imported into the Media Composer system that just exported it. (This is best to do with Composition Only/SDII OMF files as it could be very time consuming using the Audio Only method.)