I have had my Epson R1800 since 2005, so I am pretty familiar with it (currently I am using it on my Mac Mini running OSX 10.6.8, Photoshop CS5, and the latest Epson driver).
Today I tried printing an 8.5 X 11 inch print, using paper of that dimension, and in the Print Settings dialog box, I selected "US Letter" as the Paper Size. Twice the print came out completely blank!
I then tried to print exactly the same image, but this time I put in 13 X 19 inch paper, and selected Super B (13 X 19 inch) as the Paper Size in the Print Settings dialog box. I realized that I would be wasting paper, but I wanted to isolate the problem. Lo and behold, the print came out fine, with large white borders, which I had anticipated.