Firefox / thunderbird font hinting broken after upgrade ubuntu 11.04

I was encountered the font hinting/smoothing were broken on firefox/thunderbird after upgrade to ubuntu 11.04, as you see the screenshot, the title has font smoothed but the Menu,URL address and the content dosen’t.

Having reset everything in gnome by remove “.gnome2″,”.gconf”,”.gconfd” doesn’t help. Finally remove this file “.fonts.conf” in home folder did the trick.