I had an issue with FireFox 3 recently where none of my cookies were being stored after I closed the browser down. For example if I logged into iGoogle and closed the browser FireFox would not remember that I had logged in already and would ask me to log in again. I ignored this initially but as the days moved on it began to bug me more and more.

I tried to download and install the latest version of FireFox but the version I was running was the most up to date. I installed it again anyway to see if that might fix the issue but it didn't. I took a look online and it seems to be an issue affecting a lot of people. Well, for me anyways, it turns out that to fix this issue was quite painless. You need to go to the FireFox profiles folder and remove a file called cookies.sqlite. In Vista this is located in C:\Users\<<PC NAME>>\AppData\Roaming\Mozilla\Firefox\Profiles\<<Session Folder ID>>. If you can't see the AppData folder you might need to enable hidden folders. You can do this by going to Windows Explorer and selecting Organize ->Folder and Search Options -> Folder Options -> View (tab) -> Show hidden files and folders.

Remember to close FireFox when trying to remove the cookies.sqlite file otherwise you will get a permission denied error as FireFox uses this when it is open. With the file removed, open FireFox back up and try to log onto a site like iGoogle. When you close your browser and start it back up again it should work perfectly for you.