In the message linked below, I spoke of problems created with the printer when an ink cartridge filled at Costco was used. I posted the below quest at that site too, but thought it might be overlooked.

Just thought my problems were over. For some reason, the printer now "recuses" itself from being the default printer and will not let me select it as the default printer. So far, the only way I have been able to print anything is to unplug the printer for quite some time, delete it via the uninstall, turn off the computer, wait a while, then plug the printer back in, then turn the computer back on, and let it reinstall the printer.
But once I haven't used the computer for a few hours, the printer "leaves the system" once again. I am at my wits ends. Any advice and/or guidance would be appreciated.

Here is a link that might be useful: Speaking of Printer Problems