It's a Mac problem more than a printer problem.
Basically the driver uses SNMP to collect data from the printer, but OSX occasionally decides that if it gets no response from a particular thing it requests (Optical Photo Conductor) then that part must be bad and needs to be replaced, instead of correctly ignoring the null response (Optical Photo Conductor does not exist in a Xerox device)
Your only solutions will be to remove and reinstall drivers of different versions until you possibly can get the error to resolve, or wait for an OSX update to get installed that will clear the error.
The error, as far as I know happens with network printers, and is not displayed just for Xerox, as can be seen on any of Apples multiple threads that report the issue.
Some of my users are seeing an error message that reads something like the following when they try to print from their Macs:
"Optical photoconductor is not working properly..."
or something along those lines regarding an optical photoconductor....
Anyone know what this is or what to do about it? It doesn't seem to be impeding printing but it is annoying.