I've been advised to upgrade everything - the Coppermine Photo Album is a very old version and there are of course more recent versions of the forum program we're using too. Call me cynical, but I think this is primarily an easy way for the webhost to put the blame squarely at my door and completely absolve themselves of any fault.
The trouble is it's not a simple process because some of the important features on the forum such as the questions on the registration form were added by modifying the original scripts. To get everything working exactly the same with an upgraded version of SMF could take me several days. I'm keen to get it done (as it's long overdue) but I can't spare the time to do it right now. Maybe in the summer there will be an opportunity to do so.