This is happening on different OS's Win 7, Win XP, Win Vista (32 & 64 Bit) OS's and various printers HP, Lexmark that we have at several different sites where we have computers. This happens on locally installed printers (LPT1, USB) and IP networked printers. ALL printer drivers are current and worked correctly under Firefox 3.6.15. Print previews show the correct printers but only shows the URL's on the top of the pages which is all that prints, it even happens on when trying to print pdf's. This is happening on all fifty computers that we have that have been upgraded to ver 4.0 from ver Firefox 3.6.15. Updates made within FF update tool. Same thing happens with all add-ons disabled on all computers. Read all knowledge base items on printing problems none helpful. Obviously, something is not working right. Any suggestions?