I sorted it now
Apart from deleting the "mucked" lines from the HUDs I'm using, I also deleted those lines from the ones that I'm not using
But I've got another problem.
At the same time as using FPDB, I am using a software called Stud Indicator.
And FPDB's HUD sometimes thinks that StudIndicator is a poker table and it detaches it's HUD from PokerStars and attaches it to Stud Indicator.
Seems to be happening when swapping games on 8-Game mix.