It looks like you have commited your changes to tags directory. You should do it in branches. I think there is no way in SVN to force immutability of tags :(.
Just a thought -- there is at least one way to achieve this -- make a permission system (either on top of Apache, or internal to Subversion) and create two writers groups -- one for developers and a 'god mode' group for those (or that person) who can create and alter tag directory.
D.
