My issue is the following.
Ever since the introduction of Blizzard new combat log and chat settings, I seem to have trouble with any extra addon in that direction.
When the last Patch came, I wiped my WTF & Interface clean, downloaded TMP (wowinterface.com) and ran it.
It uses "Chatter" instead of "Prat".
Now, I am unsure when and where it started to mess up things again, but soon after my combat log does not work properly, nor can I adjust my chat settings.
They will not be saved at all.
When I open the chat settings from Blizzard, it's all blurry and in the wrong places.
If I have the time this evening, I'll upload a screenshot to make my point clearer.
Now, I do not have a problem with getting rid of Chatter and any other chat program.
But even when I delete the necessary files under WTF and remove the AddOn itself, it's still messed up (Blizzards default, at least).