First you need to verify that your Linux distro version is compatible with Firefox 4.0.
http://www.mozilla.com/en-US/firefox/4.0/system-requirements/

Most older Linux distros that came with the Firefox 2.0 version didn't even support Firefox 3.0, much Firefox 4.0. I have EeePC 900 that came with Xandros and Firefox 2.0, I updated the GTK package to get Firefox 3.0 to work and found the performance horrible. I ended up installing Ubuntu 10.04 that came with Firefox 3.6 and now my EeePC runs better than it did when it was new 3 years ago.

Thanks. I had a look and Ubanto file big. I am on the road for a couple of weeks so I will download when I am home and have time. I ws just hoping for an easy and quick fix. Thanks for taking the time to reply. I have an old eeepc 701. We may even just update the whole laptop. Dave

You're welcome.

Please click the Helpful button next to the answer that solved your Firefox support issue, when you are logged in, so this thread gets marked as Solved.