Forms Authentication worked great forever...Unitl i upgraded to 1.1 and vs.net 2003

The Code I have in the page load of every protected page is:

If Context.User.Identity.IsAuthenticated Then
     If Not (TypeOf context.User Is SitePrincipal) Then
       Dim newUser As New SitePrincipal Context.User.Identity.Name)
       Context.User = newUser
     End If
End If

If Not (TypeOf Context.User Is SitePrincipal) _
     OrElse Not CType(Context.User,
     Accounts.Business.SitePrincipal).HasPermission( _
        CInt(SupervisorPermissions.ViewForms)) Then
           Response.Redirect( _
   "/ThePhileVB/WebModules/Accounts/Login.aspx? ShowError=true", True)
End If

Well now, when I login to via login.aspx my FormsAuthentication.SetAuthCookie(EmailAddress.Tex t, False) and a cookie is indeed set in my \cookies directory as usual. However as soon as i navigate away from the login.aspx page Context.User.Identity.IsAuthenticated is always false!!
its like the authentication isn't happening!

I cant' figure it out! web.config is the way it always has been :
  <authentication mode="Forms" >
        <forms
            name="ThePhile"
            path="/"
            loginUrl="/Project/WebModules/Accounts/Login.aspx"
            protection="All"
            timeout="30">
        </forms>
    </authentication>

it has to be something with the upgrade to 2003 and 1.1 any help is mondo appretiated!!!

Did you delete all your .dll and .pdb files when you upgraded the version? You need to start with a clean slate.

This will be difficult for you if you're not experienced with multiple-project solutions because the dependencies haven't been set up right to allow a clean compile the first time. This may take several hours to work through.

Eric

I did delete the .pdb and .dll files from everywhere within the website (except for 3rd party dlls of course). I still have the problem but here is what i don't understand: I am authenticated on the login page and when i redirect im not authenticated but if i go back to the login page i now am authenticated and my "Authenticated User Panel" Shows up. So is it a problem with the sessionstate? It obviously reloads my login page and gives me the authenticated panel so that page knows im authenticated.

I've been using an implimentation of the phile in production for about 2 years (Thats why i havent bothered to upgrade) but i didn't realize the project dependancies where out of whack. What order should they be in and ill fix em. Thank you very much for your help Eric it seems your a power poster on this book!

Solved:

Added the following to my web.config inside the application
under system.web

  <machineKey validationKey="AutoGenerate"
            decryptionKey="AutoGenerate"
            validation="3DES"/>

I hate upgrades. Thanks for the help everyone.