help, my computer keeps saying stopped

can someone help me, on the bottom left corner where when you click on any web site or what ever you are doing on the computer, on the bottom left screen , well i notice that every now and then not all the time, i notice that my computer gets super slow and then i notice that on the bottom left it says stopped and i have dsl, does any one know why it could be doing that? thank you

 

also, I am using Windows XP and service pack 2 and my browser is firefox 3.0

 

This Firefox link should help

http://support.mozilla.com/tiki-view_forum_thread.php?locale=fr&comments_parentId=54992&forumId=1

Let us know how you get on and what you have tried to resolve it, whether you are successful or not.