I tried putting the fonts that were given to me into the library/fonts folder and had the same problem. (These fonts were from an indesign collect for output).
I then when and found that i actually had the same fonts in my own collection. I replaced them in the font folder and it seems to work now.
I just hope that when i send the files back to my client, they don’t have the same problem.
Thanks thumbslinger. What do you use to load fonts?