Digital BW, The Print

Odd artifacts found on the left hand side of a centered print (as 
viewed emerging from the 2100 printer) when using 13"x19" paper.  
Doesn't happen on A3 size.  The image is 2400x3182 at 240ppi = 
10"x13.26", and its perimeter is stroked with black to give an 8 
pixel border.  A photograph of part of the left border of the image 
on the print can be seen at:

http://homepage.ntlworld.com/j.houghton/artifact.jpg

This is a narrow image and needs to be viewed at 100% to see the 
rogue printer dots clearly (on both sides of the black border line).  
The artifacts appear on images of various sizes, not necessarily 
centered.  They appear in blocks along the whole length of just that 
side of the image and affect every print to 13x19 paper. They can be 
prevented by either adding a small extra white border to the image or 
defining a slightly smaller custom paper size.

Using QTRGui 2.1.5 and QTRPC 2.1b on WinXP Home. 

Is this unique to my system, or has anybody else come across this?

John