Why in Windows 7 Internet Explorer keeps asking me for credentials

I have recently installed Windows 7. As a new installed system, it runs faster than my old Windows XP which serverd me two years. But one things annoys me for a long time is that it keeps asking me for name and password.

I have figured out the solution:

in internet explorer-->Internet Options-->Security,
For Internet, Intranet, Trusted Site, click customer level and in popup dialog scroll down to the bottom, set "User Authentication", logon from "Automatic logon only in INtranet zone" to Automatic logon with current user and password.