Currently using Ubuntu 10.04. Certain websites such as "Classmates.com" cause the Firefox web browser to shut down.
When the classmates.com website is called up the page appears as requested but as soon as the transfer of data is complete the page disappears and the Firefox browser, not the system shuts down.
There is a similar problem with the Fedex tracking website. The page appears for less than a second ant then the status indication at the bottom left of the page indicates that the page is stopped.
We can't provide you any support with Firefox 3.6. If you want to update to Firefox 20 (which may require an upgrade of ubuntu to a more modern version such as 13.04) and you still have problems, we can help. But Firefox 3.6 is no longer receiving support or updates.
The Awesome thing with Ubuntu is you can upgrade for free :) Take an hour or two this Saturday, update to Ubuntu 13.04 and you'll not only have an OS that will receive updates in the future (10.04 stops getting updates this month), is faster, and has a modern browser than can take advantage of the modern web :)
That kind of computer expertise is above my pay grade. We'll just carry on with Ubuntu 10.04.