>Have you added xerces-2_6_2/xercesImpl.jar and xml-apis.jar the Classpath?
Maybe that is the problem. The missing class "org.apache.xerces.parsers.SAXParser" is inside xercesImpl.jar.
I use the document validation inside a plugin for a java program called "poseidon" (http://www.gentleware.com). The plugin is a .jar-file that is loaded by poseidon. The plugin jar-file uses some jar's from poseidon, they are inside poseidon program-directory/lib. I tried to copy xercesImpl.jar to poseidon lib-directory, I also tried to include it into my plugin jar-file - but that doesn't help. I am not sure if there is another classpath i have to use and where to find it (I use win XP and JRE 1.4.2).
Maybe you have an idea?