Thanks for the questions. No, we haven’t added anything new. We have tried to update the plugins, etc that are currently on the site, but I think the last updates done were a month or two ago.
It is also hard to test if it is a particular plugin, because we need all of our plugins and once the permalinks are updated again, the site works for a period of time. So turning plugins on and off won’t have an immediate effect and we’d just have to sit and wait a couple of weeks to see if the problem reoccurs, which would then lead to another slew of complains from clients because deactivating the plugins will also cause the site to not work properly! LOL