Monday, I really had problems printing (from Ubuntu) any kind of documents to the network printer of my company (which is a HP LaserJet 4050 PCL). Printing a testpage was working perfectly, but printing PDF, DOC, XLS, ... was not working. It always wanted to use "tray 1", which is used for envelopes. So the printer was telling me: "I'm not able to print such a page on an enevelope". Yeah, d'uh! :p. But whatever I tried, the printer was not planning to use "tray 2", which has A4 papers.
And to let it sound more funny: I didn't change anything to my configuration :-/
I spent 2 hours searching for it. Luckily, my French colleague helped me out on this one. It seemed that an Ubuntu package update changed my /etc/papersize file:
<a href="mailto:jochen@baileys">jochen@baileys</a> ~ $ cat /etc/papersize letter
In every application, the papersize was configured as letter (or sometimes US letter). By changing the papersize to a4 (mind the lowercase character!), I was able to print again!
<a href="mailto:jochen@baileys">jochen@baileys</a> ~ $ cat /etc/papersize a4
REMARK: I didn't have to reboot my machine to pick up the changes, however, the trick didn't work for Firefox. Even if restarted Firefox, papersize was still on "letter". I had to change it manually using : File > Page setup... > A4