Sorry but all of the pages work for me when using Firefox 3.6.6. Have you tried emptying your browser cache?
Thanks for your advice, I have resolved the problem.
I didn't want to lose all my cookies information so I ha to figure out other solution
In the dialog Tools>Options>Privacy>remove individual cookies
I have search ALL the cookies that were related to wordpress.org and deleted them.
This has resolve my situation. But I would like to know why did it happen?
Cheers
Possibly a corrupted cookie file?
Just to add that I'm also currently experiencing this problem.
There's a known issue with the new codex authentication system and old cookies.
For the time being, I think I've eliminated the problem with a quick fix. A more complete patch will be forthcoming.
If you do get that message, simply clear your cookies and reload the page, then login with your WordPress.org username and password.