Digital BW, The Print

I've come across a disturbing problem in printing B&W photos with 
ImagePrint [OSX] on my Epson 7600: in even-toned black areas there are 
"striations" [this is not "banding"] about 1/2 inch apart; there 
striations are some lighter in tone and about 1-2mm wide. The problem 
is definitely not with the printer because when I print the same image 
with the Epson driver and an Atkinson profile, the black areas print 
correctly, without any striations.

I have not observed this problem with IP color prints, but I should add 
that when I was making color prints, I used Photo Black and Premium 
Semi-Matte paper. The current B&W prints which are showing this problem 
are with Matte Black on EEM and Photo Rag.

I have informed ColorByte and will post when there is a solution.

--Mitch/Bangkok