Since adding Invisible Defender, my site does not validate as XHTML 1.0 transitional compliant. See http://validator.w3.org/
The error I get is
***
value of attribute "clear" cannot be "both"; must be one of "left", "all", "right", "none"
... lue="1" /></div><div><br clear="both" /><p><small>Protected by <a href="http: ...
The value of the attribute is defined to be one of a list of possible values but in the document it contained something that is not allowed for that type of attribute. For instance, the “selected” attribute must be either minimized as “selected” or spelled out in full as “selected="selected"”; a value like “selected="true"” is not allowed.
***
I've updated the plugin
echo '<div><br clear="both" /><p><small>';
So it reads
echo '<div><br clear="all" /><p><small>';
It all seems to work fine and validates as XHTML 1.0.
T