Digital BW, The Print

Hi all

I am having a problem printing an image with my 2100 and QTR (supplied curves 50-50 
cool/warm, 1440x720dpi on EEM).  The printer's dithering seems screwed up and is 
leaving a horrible streaking effect in an area of the print which should be plain black.  The 
effect does not appear on-screen in CS.  I have scanned the problem and posted it here 
(left image).

http://homepage.mac.com/stevekale/PhotoAlbum14.html

Notice the right side of the first print.  The area of odd dithering slowly narrows from both 
sides and is eventually no longer an issue as it gets further into the print.  But it leaves 
behind a horizontally area of fine streaks.  I have swapped out the MK cartridge and again 
and again but the damaged portion is consistent.  The portion of the image in question 
has not been edited (other than levels and some mild sharpening along with the rest of the 
print).

As a further test I rotated the image 180 degrees and printed it again.  The effect kicks in 
across the whole of the black space, slowly narrowing from each side.  The second image 
on the web page depicts this.

Any help would be appreciated.

Thanks 

Steve