If Firefox update page keeps coming back each time you start Firefox, try the following:
- close firefox
- go to your firefox profile folder
- find prefs.js file, and open it in notepad
If you find an html line at the bottom that starts with a tag "<" and a word like "ScRiPt", just delete that line.
Then save prefs.js
Now start Firefox, then close it, then start it again, and the update page should be gone.
Found this on another site, Hope it helps with your problem!:)