I have a weird firefox problem. I find that everytime I close it and open it switches back to original settings (default) for firefox and any add-on I have. Website cookies and history are intact, but the firefox tab settings, download settings etc are back to default and it goes to the default paga again.
I have tried reinstalling it clean and updating regularly - no change at all.
I have firefox 3.0.6 and use Windows Vista.

Check that you do not start Firefox in Private Browsing mode (Tools > Stop Private Browsing is grayed)
Tools > Options > Privacy, choose the setting Firefox will: Use custom settings for history
Un-check: [ ] "Automatically start Firefox in a private browsing session"
You enter Private Browsing mode if you select: Tools > Options > Privacy > History: Firefox will: "Never Remember History"

Also make sure that you do not use Clear Recent History to clear the Cookies and the 'Site Preferences'.

Is your Firefox problem a result of malware? Malware is short for "Malicious Software". It is a term generally used for software installed on your computer that is designed to infiltrate or damage a computer system without the owner's informed consent. Computer viruses, worms, trojan horses, most rootkits, spyware, dishonest adware are different types of malware.

Thanks guys! I had a similar problem with my firefox but to find out, it was a virus messing my firefox.

Hello friends,
I have a same problem of firefox.
I tried your stuff still its not working. The add-ons which I install will not work, as per my knowledge the history is different then saving settings.
The change in setting is not been saved that is the issue. I don't think I have any virus in my computer as I am using the latest versions of AVG free and updating daily. My firefox version is 3.0.8.
Any help will be great appreciable.
Thank you.

I've had a similar problem in the past, the solution (for me) was to disable my firewall - it had been hyperactive and was somehow preventing firefox from saving a profile (or something like that)