Hi Dan,
Look like your using the relatedRecordLookupFunctions plugin. We don't officially support that but try this:
Go to line 102 in /cmsAdmin/plugins/relatedRecordLookupFunctions.php and try putting @ in front of the split function, like this: @split
That will tell PHP to hide warnings for that function. What likely happened if your web host upgraded PHP and the newer PHP is now throwing those warnings.
Let me know if that works for you.
Dave Edis - Senior Developer
interactivetools.com