Thank-you for your replies - and please accept my apologies for not responding sooner...
It looks like updating my version of The Forum is definitely the way forward...
However, to compound this issue, my ISP has just upgraded the platform onto which my Forum is currently located.
I presume that the IP address will have changed as part of this move - but I can't now access The Forum's control panel, and instead get the following error message...
UBB Message
We encountered a problem. The reason reported was
Database error only visible to forum administrators
Please click back to return to the previous page.
* The 'back' button here is a link to the previous page in my browser history.
Is there another way to get into the Control Panel? Many thanks in advance.