This is not a malfunction of SVN. Those lines appear when you do an update, in case of conflict. This conflict comes from the fact that you did modifications to the file ui.rb and that someone also did modifications to this file, in the SVN server (i.e. committed his modifications), on the same line(s). In this case, SVN do not know how to merge the two batch of modifications and tells you that by putting those lines, to present the different versions (local and in the SVN server) and by putting a "C" in front of the file name when the running the svn update command.

The best way to fix this, when you don't care about your local changes, is to run svn revert ui.rb. If you do care about your modifications, you have to manually merge the different versions of the conflicting lines and run a svn resolved.