I searched google, and only found a mention of this in a MagicWorld thread. I renamed my modpack folder to pull a fresh, untainted copy down, then threw my map into the Saves folder. Got the below lines spamming my log. The first only occasionally, the 2nd every 1-4 seconds.
You can try a /cofh killall
It stands to reason if you have a mob with a mismatched ID, one way to fix it may be to make the mob no longer exist.