User Agent: Mozilla/5.0 (Windows NT 5.1; rv:21.0) Gecko/20100101 Firefox/21.0 (Beta/Release) Build ID: 20130511120803 Steps to reproduce: Updating from Firefox 21 to 22 following usual automatic updates procedure. System: Win XP 32; Screen setup: 1280 x 800 @ 120 ppp. Actual results: After updating, Firefox 22 started displaying all websites at a gigantic size, text and images alike. Downgrading Firefox back to v. 21 solved the issue. Expected results: Firefox 22 must display properly all websites regardless user screen setup, as all versions until 21 did.