IIS response 302 until it hit response code 414

Hi,

Intermittently, my application will encounter response code "414 Request URI too long" when saving the form. I use Developer Tools and noticed that there are a lot of response code 302 from the IIS server. It seem like a redirect loop somewhere. As you can see below (the network traffic I capture using Developer Tool) the returnUrl keep increasing until it hit the response code "414 Request URI too long"

<entries>
<entry>
<request>
<method>POST</method>
<url>http://localhost/TestWeb/Layout/SaveLayout</url>
<postData>
<mimeType>application/json</mimeType>
<text>{"LayoutId":-1,"LayoutName":"Test"}</text>
</postData>
</request>
<response>
<status>302</status>
<headers>
<header>
<name>Location</name>
<value>/TestWeb/Account/LogOn?Mode=win&amp;ReturnUrl=%2fTestWeb%2fLayout%2fSaveLayout</value>
</header>
</headers>
</response>
</entry>
<entry>
<request>
<method>GET</method>
<url>http://localhost/TestWeb/Account/LogOn?Mode=win&amp;ReturnUrl=%2fTestWeb%2fLayout%2fSaveLayout</url>
<httpVersion>HTTP/1.1</httpVersion>
</request>
<response>
<status>302</status>
<headers>
<header>
<name>Location</name>
<value>/TestWeb/Winlogon.aspx?returnUrl=%2fTestWeb%2fLayout%2fSaveLayout</value>
</header>
</headers>
</response>
</entry>
<entry>
<request>
<method>GET</method>
<url>http://localhost/TestWeb/Winlogon.aspx?returnUrl=%2fTestWeb%2fLayout%2fSaveLayout</url>
</request>
<response>
<status>302</status>
<header>
<name>Location</name>
<value>/TestWeb/Account/LogOn?Mode=win&amp;ReturnUrl=%2fTestWeb%2fWinlogon.aspx%3freturnUrl%3d%252fTestWeb%252fLayout%252fSaveLayout&amp;returnUrl=%2fTestWeb%2fLayout%2fSaveLayout</value>
</header>
</response>
</entry>

I am using IIS 7.5, .Net 4.0 for my application. Any ideas what could be causing this?

Thanks in advance.