Hm. What bit rate are those WMA files? I remember that there used to be a bug (that I thought got fixed) where WMA files higher than a certain bit rate would get an error. I don't remember what that bit rate was, or if the error manifested itself in the way you describe.

I also seem to recall this question coming up before in the past, and I don't recall how it was resolved. Anyone got a link to that discussion?