I use bugsack to monitor for LUA errors, and this one is constantly popping up on it.
99x FrameXML\ChatFrame.lua:1060: bad argument #1 to ‘strlower’ (string expected, got nil)
[string “=[C]”]: in function `strlower’
[string “@FrameXML\ChatFrame.lua”]:1060: in function <FrameXML\ChatFrame.lua:1055>
Locals:
(*temporary) = nil
(*temporary) = “string expected, got nil”