Looking at the screen shot you have supplied of the driver, it would seem that your driver has not been properly installed. You should have a lot more options than those shown in your screen grab including Print Settings. I have come across precisely the same problem as this when setting up my cousin's new 3800. I suspect that there is a conflict earlier versions of an Epson driver and the one you have just installed.
You need to reinstall the driver again. I would suggest that you delete the printer via System. Then trash all existing drivers. Whether or not this affects the 3800 I don't know but when I was having trouble with a 2100 driver, Epson support told me to trash all references to Epson from the Library/Receipts folder as well. So I would suggest that you do this. Then do a repair disk permissions, restart, repair disk permissions again and install from scratch.
This should solve your problem.
Good luck.