After installing June 2011 CU for SharePoint 2010 Server, you start to get errors in your InfoPath form. After disabling Security Validation in the Web Application General Settings, you realised that you cannot create anything from the UI.
As a work-around, you need to modify FormServer.aspx located under \Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\LAYOUTS and add the line in bold:
<body runat=”server” id=”PageBody”>
<SharePoint:FormDigest runat=”server” />
Do an IISRESET and the error should disappear.