Asp.Net MVC AllowHtml attribute fails on postback

Asp.Net MVC AllowHtml attribute fails on postback

i am having troubles trying to use a rich text editor in Asp.Net MVC.
Actually i have the field that contains the RTF marked with the
[AllowHtml] attribute and it's working right in the model binder, so i get
the html value in the post method of the action.
But then, while rendering the response, in the layout page we access
another property of the request directly using
ViewContext.HttpContext.Request.Params["paramname"] and there it throws an
HttpRequestValidationException because of the value of the text field,
even if it's not the form parameter we are trying to access.
Any clue about how to avoid this?
Thanks!