First thing to do is to check to make sure that version of Linux meets Firefox 4 system requirements. <br /> http://www.mozilla.com/en-US/firefox/4.0/system-requirements/ AFAIK, most Linux distros that came with a Firefox 2.0.0.x version don't even meet Firefox 3 system requirements, much less Firefox 4 system requirements. Usually the GTK package isn't new enough for the newer versions of Firefox. ''I encountered that situation with my Asus EeePC 900 netbook, which came with a two year old version of Xandros and Firefox 2.0.0.9. After messing around with it for a few weeks and installing a later GTK package and found it slow as a dog, I eventually installed a different version of Linux that came with a new version of Firefox. Works better than it ever did with the original operating system.'' It's possible that the upgrade that was offered to you when you did the restoration to factory settings included other updates that are needed to be able to run Firefox 4. Purely speculation on my part though. Why not check that out with a support forum for that brand of computer or that particular Linux distro?