Ah, OK - that makes sense. It will be the include for the navigate, which displays different options depending on the user type currently logged in. Will need to have a think about how to best proceed, as there are about 270 pages (don't ask!) to update to mySQLi.
Are you able to email me the versions you have, and I'll re-upload the version I have here. And look at creating a duplicate version of the site somewhere to work through the mySQLi changes.