I'll preface this by mentioning I've never attempted any sort of theme editing, or fiddling about inside the themes.ini file, but what you are describing is not normal behavior. Granted another member just recently posted with similar "returning to default themes" problems, to which no resolution has currently been found and/or confirmed. I have however tried and used so many of the themes, I couldn't tell you how many, and I have never encountered the issue you are experiencing. I believe this may be one of the reasons this thread isn't seeing many responses, but many times the right answer comes from a member who only logs in once a week or so. The only suggestion I have is downloading a new copy of the current release and simply reinstalling it. It sounds like something has become corrupted, and this may correct it. This should go off without a hitch, but it's always good to maintain a backup.