(1) When installing a new version of mp3tag (previous versions removed, all relicts manualy deleted, checked the registry that there is hopefully nothing related to MP3tag), the installer briefly displays "Copy failed" as the very last message on top of the progess bar (see the attached image). This does not seem to be affected by different installation options and I can reproduce it for the default install any time. Interesting thing is that this failure does not seem to affect the behaviour of the program.
(2) When deinstalling, last beta builds always leave the file Mp3tagSetup.ini behind, regardless what I click when the uninstaller asks me if I want to preserve the setup files or not.