QTR-Quadtone RIP

I've just started using Hahnemuhle Photo Rag, and I'm getting vertical 
banding on large (13x19) prints on Epson 2200 (UC inks)--doesn't show 
up on letter and smaller. I've used both the sheet feed as well as the 
manual feed, with same problem. Printing on Enhanced Matt is fine 
(Windows XP).  

Also, after downloading the latest update, I get a fatal Windows error 
in the Image to Raster (shuts things down, but keeps printing, 
luckily).

Any help will be greatly appreciated.