asp.net session dissappers

I have a strange problem: I have a site which has an administration system.

In the system there is a way to edit my inputs. To make this easier, I can search for their ids to find them.

The problem is when the page posts back the session variable I hold the "logged in" value in, becomes nothing.. and i get kicked out. Why is that happening? Session variables should hold at least 20 minutes if anything else is stated?

EDIT: It works for a coworker, but not for me.. Also, it only does it on certain inputs.

EDIT2: Turns out i get an exception. but it doesnt say what, only says "property evaluation failed". i get it on this code row:

Response.Redirect("./admin.aspx?search=" + u.FirstOrDefault.ProductID.ToString, False)

And sience it goes through this statement, its not because it is an objectreference not set to an 开发者_JAVA百科instance of an object

If u.Any Then

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If you experience an exception your session might be restarted. Create a global.asax and set breakpoints to the Application_Error, Session_End and Session_Start events to track down the issue

Edit based on your update: Make sure that u.Count == 1, because FirstOrDefault will throw an exception, if the count is > 1.

Have a look at this link http://support.microsoft.com/kb/312629/EN-US/ which should cover your original problem http://forums.asp.net/t/1296202.aspx/1

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If you have Web Garden enabled (multiple worker processes for an application pool) this can explain such behavior - been there.

Either have one worker process for the pool, or switch to Database driven Session.

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Do you have cookies enabled? If not, this would explain this behavior. Especially as you state it works for the co-worker, you can deduce it's a client-side issue.