Digital BW, The Print

Hi All, 

I just got a new epson 4000. So far I'm very happy with the results 
(in color, not b&w, but thats to be expected. my BW sepia tones look 
great.) but a strange problem appears with large custom sizes...I'm 
trying to print some banners on 17" roll paper using the epson driver 
set for "borderless banner" on my Mac running OS10.3 with PS CS. This 
works when I set the custom print size at 16x44, but when I set it to 
17x55, it prints only a small (around 8x10inch) portion of the image 
at the wrong orientation. Am I running into the old epson driver 
44inch limitation? I thought that had been fixed with the new drivers 
for the 4000. What is the print length limit on this printer? I've 
seen it quoted at 100', and someplace else at 56". How can I make 
bigger prints? do I need to get a RIP? 

Best regards,
Neil