Strange printing effect

[Barry Samuels <barry@beenthere.mail1.co.uk>]

I use Debian Testing/Squeeze with the 2.6.32 kernel, hplip and hplip-cups. 
My printer is a networked HP LaserJet 4500 colour laser.

I get a strange print output sometimes where parts of the background are 
black where it should be white. This only occurs on areas which are empty 
i.e. there is nothing there to print. The areas which have text do have a 
white background.

The easiest way to understand is to look at this image of a printed page:

http://www.beenthere-donethat.org.uk/system/print-sample.jpg

All those black bands and lines shouldn't be there i.e. they should all be 
white.

If I print a CUPS test page it prints perfectly. If I print a text 
document from the OpenOffice word processor this effect does not show but 
if I print a spreadsheet from OpenOffice it does show.

A print from the Iceweasel browser shows some thin lines on the outer 
edges only and printing from a PDF document using the Adobe Reader 
produces the black baground effect.

It's all rather baffling and any suggestions would be greatly appreciated.

-- 
Barry Samuels
http://www.beenthere-donethat.org.uk
The Unofficial Guide to Great Britain