EFI had some really weird issues caused by DST with various drivers. I believe they fixed it for most models but can only confirm it was resolved for sure with the 560.
Best bet for unfixed drivers is to disable the following 3 things.
But, as stated, EFI has pretty much solved the issue with newer drivers, but those drivers cannot be found on Xerox.com, always get the drivers for EFI rips from EFI.
Things to note, make sure you don't just update the current driver, remove it, remove the port and install fresh. And keep this issue in your mind as DST is about to end, and if the driver has not been fixed, it will happen soon after November 1st.