AbsoluteURI stored in Session - Not working in IE

This is a really strange problem for something that should be simple.
I'm storing a URL - which contains search strings - into a session so I can create a 'back to search' link on the item page.  It works in Firefox but in IE it only brings back the URI without any parameters
Dim back As String = Server.UrlEncode(Request.Url.AbsoluteUri.ToString) Session("back") = back

and then to read it...


btnback.NavigateUrl = Server.UrlDecode(Session("back"))

In Firefox I get the full URI but in IE it only returns http://localhost:6666/Search/Default.aspx

Any ideas?
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