java.lang.ClassNotFoundException: org.apache.xml.resolver.Catalog

Hi,

I'm getting the error "java.lang.ClassNotFoundException: org.apache.xml.resolver.Catalog" for the below code.
I'm using Tomcat 7.

mvc-dispatcher-servlet.xml

Web.xml :-

HelloWorldPage.jsp:-

I'm getting this error for other projects as well.

My build path contains : -
org.springframework.beans-3.1.0.RELEASE.jar
org.springframework.context-3.1.0.RELEASE.jar
org.springframework.core-3.1.0.RELEASE.jar
org.springframework.web-servlet-3.1.0.RELEASE.jar
org.springframework.web-3.1.0.RELEASE.jar
jstl-api-1.2.jar
standard-1.1.2.jar

Please advise.

adding metadata-complete="true" in <web-app> does solve the problem but I need to know the reason for this error.
Also corrected the build path with more jars .

Please advise.

Regards,
Pramod Talekar