OK, I can see this isn't a bug but I haven't done the above. So, I guess, before 'updating' MaxGUI I need to delete it first. Is that right?
If you haven't edited the files (even by accident), then your SVN client may have got confused and marked the files as having changed when they haven't. In which case, if you delete and checkout the files concerned, it shouldn't happen again.
What SVN client are you using? Command-line? TortoiseSVN?