Not saying this is directly related to the issue, but don't forget this version of SMF is old, and without an upgrade it will stop working correctly one day. You might think it works now so why not forever, well, other software that supports this forum software is being constantly updated, such as the server operating system and each time it does the risk of an incompatibility is there. Also dont forget the security fixes that have been rolled out in more recent releases which may protect your information better and prevent intrusions into the database or frontend. This version (1.1.20) has been out of date for a long time now and the advice to upgrade to version 2 must have been about a year or 2 ago by now. Just saying dont be surprised if the site goes offline for a week or more at some point.