This is a Mac setting.

1. Click Accounts (in the System row of the System Preferences window)
2. Click the Login Items tab
3. Click on Firefox in the list of applications
4. Click the "-" symbol

Thank you, thank you, thank you! Now maybe I'll get my sanity back! Oh, really, that'll never happen, but thanks anyway. At least I won't be quite so nuts when I turn on the computer!

I have same problem, runs on start-up with Windows Xp. How do I make it stop?

This is not the solution for me. Checked preferance under login nothing there to remove. Any other solution? I'm on Tiger 10.4.11. The other option is not to select Firefox as the default. I think I'll do that for now until this is resolved. Very annoying indeed.

these replies are for Mac, nothing for Windows

For those of you running Windows, I found this on another site. (Unfortunately, not before getting totally disgusted and switching to chrome.)

1. click start (or the windows flag button at the bottom left) 2. in the "search programs and files" or the RUN dialog box, enter "msconfig.exe" or "msconfig". 3. That should open the system configuration program. 4. click the "Startup" tab at the top of the opened program. 5. Under the "startup item" column, look for Mozilla firefox. 6. uncheck that one. 7. Click OK or apply. 8. click "exit without restart". 9. you're good to go.

go to the firefox folder...c:\program files\...then find the icon name updater..delete that..and another icon named.update.ini file ..delete that too..problem resolved.