This only happens in IE, it's ok for chrome and firefox.
This is a known issue which can be solved by check "Sign me in automatically" when login.
Because of security issue, user needs to sign in next time he access sharepoint, so I can't use "Sign me in automatically"
What I really need is user don't have to check the "Sign me in automatically" when login, and still I can get rid of the login popup when user open office doc from document lib in IE.
Can I add a http module or something?
Any help is greatly appreciated! thanks.