This page is sending dangerous requests since it is using a rich text editor that post HTML. This was worked around before by putting
ValidateRequest="false"in the page declaration.
This seems to be ignored now in .NET4! Really I should be changing TinyMCE to be posting BBCode and replacing it with proper HTML on the server... but... I'm not since this is only for trusted internal users... and I can't be bothered ;)
WorkaroundrequestValidationMode="2.0" needs to be added to the httpRuntime element of the
<system.web>section of the web.config.