Looking for good xhtml explorer

Dear XML Specialists,

I need to debug some xhtml document but could not find a decent working free xhtml explorer around. The xmlassert-full.jar downloaded from http://sourceforge.net/projects/xpe/files%2Fxmlassert/
could not be run with the following error:

JAVA_HOME=C:\Program Files\Java\jdk1.7.0_03
OS=Windows_NT
Path=C:\Program Files\Java\jdk1.7.0_03\bin;...

C:\>java -jar xmlassert-full.jar
no main manifest attribute, in xmlassert-full.jar

On the other hand, xpathexplorer0.1.3.zip from http://www.antepedia.com/detail/p/282834.html consisted of source code and require further instruction to compile it properly.

These XHTML files have been saved from Firefox as HTML files instead.

I am running Java 7.x, Netbeans 7.2 on Windows XP / 7 platforms.

Your assistance woudl be much appreciated.

Thanks in advance,

Jack