Problem with processContents="lax" in MSV

Hi all
I am using MSV in order to validate XMLs, but I am facing a problem with the
lax processing.
It seems like the lax is working fine with undeclared elements (it does not
validates elements which are not specified in the XSD), but it throws
validation error on undeclared elements, which contain attributes. This kind
of behavior does not happen in other validation tools (such as "XmlSpy" has,
for instance).
The XSD looks like:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="unqualified" attributeFormDefault="unqualified">
	<xs:element name="Root">
		<xs:complexType>
			<xs:sequence maxOccurs="unbounded">
				<xs:any processContents="lax"
maxOccurs="unbounded"/>
			</xs:sequence>
		</xs:complexType>
	</xs:element>
	<xs:element name="InnerElement" type="xs:boolean"/>
</xs:schema>
The XML looks like:
<Root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="C:\temp\lax.xsd">
	<InnerElement>true</InnerElement>
	<UnDefineElement attr1="1"/>
</Root>
The error tells about "unexpected attribute 'attr1'".
Is it a bug?
Can someone help?