Hi, i've fixed my problem using the information in the blog http://dotnetfish.blogspot.com/2012/05/facebook-invalid-url-requested-url-is.html , hope this can solve your problem as well. It's not able the browser but the setting in hosts file.

The first thing is that I suggest you upgrade to Firefox version 12. New releases include security patches that are important for safely browsing the web.

If you can't connect to facebook from other browsers either then I don't think this is a firefox issue.

Can you access facebook through a proxy? Try through Hide My Ass

now can access already after changing some code thing from the blog.Thanks man =)

Glad it is working now.

Did it suddenly stop working? If so it may be that a virus or worm modified the hosts file. I'd do a full virus scan.

Yea. The info in the blog really helps.

i did a full virus scan,but turn out no virus detected it just suddenly stop working during afternoon. it may be possible cause the previous night i turn off my firewall cause was playing LAN games with friends. Just letting you know...

That does sound like spy/malware to me. See here:

http://antivirus.about.com/od/securit.../hosts.htm

Maybe try a full scan with malware byes or spybot s&d just to be on the safe side.

thanks man...really appreciate it =)