I have had successsith the following procedure:
Download audiobook.
Open and play a few seconds in WMP. (This takes care of the DRM.)
Copy to Zen Microphoto via MM.

I'm not using an IPod (not a big fan of Apple myself). My player is a Creative Zen Microphoto. I have gotten a drm error in the past, but not so when attempting to transfer the files with MM. I've tried listing the genre as audio book, and even went so far as to remove every file from my player, then transfer only the audio book file. MM says that the file transferred, but it's nowhere to be found on my player. I haven't figured out the reason for the failure to transfer, but I've found a solution, in case anyone else needs a fix. I removed the MM file association for wma files, and associated the wma files with my Zen software. I also had to change the setting in MM which causes the file types to associate anew on startup. I'll just have to keep the audio books files seperate and sync them with the player software versus using MM. This doesn't seem to change the music wma files, so I guess it's a good enough fix. The audio books are 20 day check-outs only, so I won't be keeping them, and thus won't need to organize or store them. So long as I have my music and my audio books, I'm a happy camper.
Thanks for the reply. :D

Are you using an iPod.
If so audiobooks only show up in the audiobooks menu if they were downloaded from iTunes or Audible.

(Reason to hate Apple #4521345402) :P

Make sure the genre of your audiobooks is in fact "audiobook" or something simliar and then look for them in the genre menu of your iPod.

If your audiobooks have some sort of DRM I think you're out of luck.

It would help to know what player, software, etc you are using if the above doesn't help.

Also, Do the files play in MM?

I'm new to MM, and just upgraded to Gold. So far I love the music capabilities, but I'm having difficulty with audio book files. These files are dowloaded with license from my local library. I have always been able to transfer them to my MP3 player without difficulty. When I attempt to do so with MM, it says that the file is transferred, yet it does not show up on my MP3 player. I then attempted to revert to the MP3 software, and now I receive an error on that software. Any assistance would be greatly appreciated. Thanks!