I had same problems persist w/ Firefox 7. Finally solved. See https://support.mozilla.com/en-US/questions/880685

I have had this same problem for the past few months. I have searched many times, read nearly every post on every site about "possible" fixes, tried every one of those "possible" fixes, and nothing worked. Until just now. I found the following and for the last 60 minutes, I have not had any instances of freezing. It's worth a try. I don't know much about computers so I'm not sure how this may effect anything, but it stopped the freezing so I wanted to share it.

Source: http://forums.mozillazine.org/viewtopic.php?t=270174 This workaround is recommended: 1.When Firefox is started,launch the Windows Task Manager (press CTRL+ALT+DEL, or right click the clock display on the Windows Taskbar and select Task Manager) 2.Select the process tab 3.Locate and right-click on the Firefox process 4.Select the set affinity option from the popup menu 5.Uncheck CPU 1 and validate with OK. 6.You can go back to Firefox. It is essential to change this affinity setting before loading Firefox.