This add-on is designed to help track down the add-on code responsible for creating nameless frames that can interfere with gameplay. It posts an alert when such a frame is created. On logout, the file ~WoW/WTF/Account/ACCTNAME/SavedVariables/MysteryFrames.lua will contain a table of all such incidents that occurred during the last session, but thi s information is not saved between sessions.
This add-on is disabled by default to avoid annoying users with meaningless chat-spam, so you will need to enable manually for the character with whom you will do the debugging.