Firefox 3 has a new function to prevent this automatic redirection of URL to another. To set up this, run Firefox browser, click on ‘Tools’ – ‘Options’ - ‘Advanced’ and confirm that ‘General’ tab is selected.
Now onwards Firefox will report redirects with an information bar. You can allow or disallow of this, only when you confirm them with ‘Allow’ will it proceeds.
You can also opt in for Firefox add-on NoRedirect. It lets you take control of HTTP redirects. It can be used to interdict an ISP's DNS search redirection hijacks, preview/screen "shortened" URLs (e.g., TinyURL), stop the annoying redirection of "smart" error pages, etc. This add-on will give more power for controlling URL redirection and you can also add your own list from the option menu. However this experimental add-on required free account with Mozilla in order to install.