I would suggest you to install the following codec and then try playing the files again.
If the issue persists, please perform a clean uninstall and reinstall of RealTimes by following the below article:
Make sure you delete the RealPlayer folders as mentioned in the below article, before reinstalling RealPlayer.
NOTE: Deleting these folders will remove any playlists you've created; the files will remain in your library but the playlists will need to be re-created.
I wanted to let you know that we have edited your original post to remove your email address to protect your privacy. We recommend against posting any personal contact information in a public Community forum.