I'm using Tomcat 5.5.9 and I'm receiving XML parsing errors and StandardClassLoader errors when Tomcat is started, yet the XML files do not contain errors. In fact, the web applications run as if nothing is wrong. The XML errors are related to Struts and Tiles, and I need to eliminate them. What are the correct DOCTYPE definitions for web.xml, struts-config.xml, and tiles-def.xml? Here are the currect ones:
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
<!DOCTYPE struts-config PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 1.2//EN"
<!DOCTYPE tiles-definitions PUBLIC
"-//Apache Software Foundation//DTD Tiles Configuration//EN"
I don't think that it will help your problem (although it might), but you should consider upgrading to Tomcat 5.5.28. Whether or not it fixes your DOCTYPE issues, it will address some security vulnerabilities from the earlier releases.
It's most likely that your Tomcat server doesn't have access to the open internet that permits it to download the DOCTYPE files themselves and doesn't have a local copy to work from. The DOCTYPE files are used to validate the XML, and thus aren't critical, but it's still better to have them.
An IDE is no substitute for an Intelligent Developer.