Oh, I simply quoted because it contained stuff about the partyframes...
I disabled everything apart from praid and the default Blizz partyframes still showed up along praid. I even removed the SavedVariables/PerfectRaid.lua just to be sure. That makes me sure it is not connected to any other addon.
But I can /script HidePartyFrame() manually, though.
Just to have it mentioned, even if it doesn't matter: German client...