I noticed that you had the printer working with some Firefox and other applications (but not Kontact) when you posted two months ago:
I'm using 7.0.1
When I try to print something from Kontact, a mail from kmail or a news from knode, all I get is nonsense : random characters on my paper.
Firefox3 and kwrite print fine, all as it should be.
I'm using a HP Photosmart 7350 that I set up via Cups.
Is there a problem with Kontact (or is anybody having the same issue?) or a config problem somewhere ?
So I wonder, did you set up the printer with the same driver and filter under 7.0.1 and 7.0.2?
How is printing a simple file from a text editor like KWrite?
Is the Photosmart 7350 a postscript printer?
I don't have a Photosmart 7350 or other USB printer to test with, but I have had past experiences with HP LaserJets where I was given a choice of several "filters" like foomatic, Gutenprint, etc. (Filters convert the print job data into the final language and formats understood by your printer.) Make the wrong choice and you can spew out pages of random characters from a simple print job because the filter is misinterpreting the data. So -- is the foomatic/hpijs the only driver choice or are there other filters that you can test? The Gutenprint filter seems to be a common choice for HP Laserjets managed by CUPS and perhaps this will be an option to try instead of foomatic.
This link is a little old, but perhaps it will shed some light on drivers, filters, and printers:
http://www.linuxprinting.org/kpfeifle/L ... -PPDs.html