If you are using Firefox as your default browser, then either you get an IE tab add-on to view SharePoint sites in Firefox, or type your user name and password each time when you access to the SharePoint server.
There is a way thought to allow you to save your typed Windows credentials in Firefox to prevent you from repeatly typing the Windows user name and password.
Enter “about:config” in the address bar of Firefox and hit
Do a search on "ntlm", at least three entries should appear
Double click the entry titled "network.automatic-ntlm-auth.trusted-uris" and set its value to .yourdomain (do not forget the dot). You can have multiple domains by entering them as comma-separated.
Restart your Firefox to get it to kick in. Woila! No more irritating login prompts. This only works with NTLM authentication and not Kerberos.