Hello IamZhao,

because cookies are not shared between processes.
u should persist your cookie's data somewhere

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WBR,
Michael  Nemtsev [.NET/C# MVP] :: blog: http://spaces.live.com/laflour 

"The greatest danger for most of us is not that our aim is too high and we
miss it, but that it is too low and we reach it" (c) Michelangelo

I> When clicking a hyperlink in an application that is hosting the
I> WebBrowser control, a new page opens in Internet Explorer. In this
I> scenario, the session cookie seems lost, and I have to log on again.
I> Could anybody tell me how to maintain the ASP.NET session state under
I> this situation? Thanks.
I>