I see you've read the DCC Pending thread already, but I also notice you said it still doesn't work for "some" files. You will notice that one of the post's suggestions is, "-try getting a file from someone else. The problem is often on the senders end". If you can receive files from anyone else, then it is not your problem, but the senders.
For the sake of me not getting a verbal battering I won't make accusations, although I find the fact you're getting this error message (which is linked to Fserve's and XDCC bots) very suspicious. Always remember the dangers on IRC of downloading files from anyone.
Regards,