Not sure if my problem is the same, but with a brand new Espon printer and Mountain Lion, the printer initially worked and then the Mac couldn't connect to the printer after the Mac went to sleep or was rebooted. The printer was connected via Ethernet to my home network.
I had to do a fresh install of the printer software to get it to work, only to have it stop connecting again after sleeping/rebooting the Mac. Very frustrating. Multiple calls to Epson and a call to Apple too. I should mention that the problems I describe were isolated to the Mac with Mtn Lion because another Mac in the house was not having any problems with the printer. Another strange aspect was that although I couldn't see the printer on the network once it stopped working, the fax interface on the same printer continued to show up - presumably different drivers.
The "fix" for my issue was to add the printer in via itss IP address. Knowing the IP address of the printer and going through the Add Printer dialog allowed the Mac to not only find the printer, but hold the settings through sleep and rebooting.
Hope this helps