Try one more thing. Head to Epson.com and see if they issued newer drivers.
I have an Epson RX 500 and my OS is Vista. I am trying to share my printer. When going to Network and Sharing centre it will not let me highlight the box and comes up with an error message of 'Invalid Parameter' - totally baffled and do not know how to proceed. My wife's OS is XP. Any advice would be appreciated.