I have a Lexmark E460dn monochrome laser printer that worked before I got my new MacPro (Lion). The printer is in a LAN at home and an iMac on 10.6.x can still print to the printer so the printer is functioning.
With this computer, I see the printer being looked for, then am getting an error of "Print file was not accepted" and then the printer pauses. I did a software update before I did the migration of data from an older Mac to this Mac Pro. The Lexmark drivers were updated to v 2.5. Apple support yesterday had no explanation or a fix. Still waiting for a reply from Lexmark.
I have deleted the printer, and re-installed it, but it didn't help. I plugged the printer directly into the left ethernet port (internet is in the right jack) and it couldn't find the printer. I took out the internet in the right ethernet plug and plugged in the printer and I again got the file not accepted.
I put the ethernet connection into the left plug and I got no ethernet available. Moving the internet back to the right jack and internet returned.
I connected the printer via a USB connection on the printer and got the same print file not being accepted. When I plugged in the USB cord from the printer into the computer, the printer woke up, so it sensed it was just plugged in.
My guess is that there is something wrong with the Lexmark driver update for Lion and an additional problem that I might also have a bad ethernet card that only works on one of the plugs (My old Mac had to be replaced because the only ethernet port went bad). I will call Apple support again about the bad ethernet port in the morning.