Mozilla issued a small fix for Firefox 17, it patches a font rendering issue and fixes a potential incompatibility problem. Firefox browsers are updated automatically so you don't need to take any steps to download the update, although you can speed up the updating process by clicking on "About Firefox" in the "Help" menu.
FIXED: 17.0.1: Font rendering issue in Firefox 17.0 (bug 814101)
FIXED: 17.0.1: Reverted user agent change causing some website incompatibilities
