Hello Shatabdi.

Try clearing your browsing cache.

If that doesn't help, try deleting your gmail cookies.

If that doesn't help either, it's possible that you are having a problem with some Firefox add-on that is hindering your Firefox's normal behavior. Have you tried disabling all add-ons (just to check), to see if Firefox goes back to normal?

Whenever you have a problem with Firefox, whatever it is, you should make sure it's not caused by one (or more than one) of your installed add-ons, be it an extension, a theme or a plugin. To do that easily and cleanly, run Firefox in safe mode (don't forget to select Disable all add-ons when you start safe mode). If the problem disappears, you know it's from an add-on. Disable them all in normal mode, and enable them one at a time until you find the source of the problem. See this article for information about troubleshooting extensions and theme and this one for plugins.

If you need support for one of your add-ons, you'll have to contact its author.

If it's not a problem with add-ons, check if other browsers have the same issue. If they do, it's possible that it is network related, or that there's some software (like that antivirus) that's causing this problem.

I have the same problem as well. It first occured after wiping off virus', trojan horses, etc. off my lap top. I have anti malware and an anti virus and other things that were run to clean up my comp. Since then, I was unable to open gmail, igoogle, googletalk, etc. i have tried disabling the add ons, etc. that you have suggested, and its still not working. If it is indeed caused by an anti-virus, how do i fix it!?!! This is super frustrating, any help is appreciated! Thanks

ps: when this first occured, i attempted to access gmail, igoogle, etc. after cleaning the virus',etc. it warned of an unsafe/unsececure sight, or certificate, etc. I made an "exception" becuase i do trust the site but instead of going to the site, i have been getting the "Not Found

The requested URL /accounts/ServiceLogin was not found on this server. Apache/2.2.3 (CentOS) Server at www.google.com Port 443"

-(

That sometimes happens when the router has been hacked. You should never create exceptions when all https sites are displayed as untrusted. It shows it's not an issue with the sites, but with your connection.

Factory rest your router. If you don't have a router, I have no idea how to deal with this. I'm sorry.

Thanks for your feed back. what exactly is a router? i know, i sound totally igonorant, im new to the whole lap top thing. all other sites were displaying properlly, etc. so, my friend suggest i just "accept" much to my dismay... I also have IE on this lap top but FF is my default browser... just in the event that may shed some light and give me some hope?!

..how would i go about resetting or, testing the router?

A router:

http://en.wikipedia.org/wiki/Router