I was using version 3.0.
When i login with wp-admin, i can access my admin panel. (see here)
But, what ever i click next, e.g. "posts" in admin panel, it will redirect my logout with reauth=1 at the end of the url. (see here)
Methods i tried but still failed:
1) Clear cache and cookies
2) Replace new copy of wp-includes and wp-admin
3) Replace .htaccess with default
Now i upgrade to version 3.0.1, but the problem still remain. Somebody please help, thanks.