The file rename dialogs e.g. batch rename files from tags and so on, permit space characters in the beginning of the file names. This can be dangerous as I have found out. I have accidentally inserted spaces in front of the filename format string which resulted in multiple of my albums to end up with an (almost invisible) space in the beginning. Winamp could not find/play back the files from the mp3tag generated playlist files. It was tricky to find out the cause of the problem.
One such mistake in the renaming template could easily result in many many files being renamed wrong hence causing such problems. It would be wise to add additional checks for such user errors. Even a warning box would be a welcome addition.