They want you to upgrade because your version of firefox is hopelessly out of date.
I had an ISP tech support guy tell me once that my software was worn out. That could be the problem.
I find that to free up system memory I need to restart firefox once or twice a day. No Problem as long as firefox will reopen the same windows I had prior to shutdown, in the same taskbar order. 3.6.xx does that. All subsequent version do not. On restart, newer ff’s reverse the order of the windows in the taskbar.
If any freeper wants to try this on their ff version, just launch the Windows Task Manager and under the Process tab, select Firefox and right-click to End Process. When ff restarts it will have an oops msg, you select to Restore and see what the outcome is.