Form con efecto cascada

hola a todos

he puesto un <form> en un documento html y dentro de un contenedor div y me sale un efecto cascada, el formulario me sale repetido varias veces. He pasado el validador w3 y me da este error:

<em>&lt;form&gt;

The element named above was found in a context where it is not allowed. This could mean that you have incorrectly nested elements -- such as a [i]"style" element in the "body" section instead of inside "head" -- or two elements that overlap (which is not allowed).

One common cause for this error is the use of XHTML syntax in HTML documents. Due to HTML's rules of implicitly closed elements, this error can create cascading effects. For instance, using XHTML's "self-closing" tags for "meta" and "link" in the "head" section of a HTML document may cause the parser to infer the end of the "head" section and the beginning of the "body" section (where "link" and "meta" are not allowed; hence the reported error).</em>

por lo que entiendo me dice que estoy utilizando codigo XHTML en un documento HTML pero el formulario que utilizo és el siguiente:

<em>
&lt;form&gt;
&lt;label&gt;Contrasenya
&lt;input&gt;
&lt;/label&gt;
&lt;input&gt;
&lt;/form&gt;</em>

Alguien sabe como arreglar-lo?

gracias