What steps will reproduce the problem?
1. Start Eclipse
2.
3.

– Error Details –
Date: Tue Mar 19 10:36:09 PDT 2013
Message: Plug-in configuration error, extension "org.jboss.tools.jst.web.kb.FaceletValidatorExclude" references validator id "org.eclipse.jst.jsf.facelet.ui.FaceletHTMLValidator" but this id does not exist.
Severity: Error
Product: Eclipse 1.5.2.20130110-1126 (org.eclipse.epp.package.java.product)
Plugin: org.eclipse.wst.validation
Session Data:
eclipse.buildId=M20130204-1200
java.version=1.7.0_17
java.vendor=Oracle Corporation
BootLoader constants: OS=linux, ARCH=x86_64, WS=gtk, NL=en_US
Framework arguments: -product org.eclipse.epp.package.java.product
Command-line arguments: -os linux -ws gtk -arch x86_64 -product org.eclipse.epp.package.java.product

Exception Stack Trace:
org.eclipse.core.runtime.CoreException: Plug-in configuration error, extension "org.jboss.tools.jst.web.kb.FaceletValidatorExclude" references validator id "org.eclipse.jst.jsf.facelet.ui.FaceletHTMLValidator" but this id does not exist.
at org.eclipse.wst.validation.internal.ValidatorExtensionReader.process(ValidatorExtensionReader.java:86)
at org.eclipse.wst.validation.internal.ExtensionValidators.<init>(ExtensionValidators.java:43)
at org.eclipse.wst.validation.internal.ExtensionValidators.instance(ExtensionValidators.java:36)
at org.eclipse.wst.validation.internal.ValManager.getV2Validators(ValManager.java:345)
at org.eclipse.wst.validation.internal.ValManager.getValidatorsNotCached(ValManager.java:221)
at org.eclipse.wst.validation.internal.ValManager.access$1(ValManager.java:220)
at org.eclipse.wst.validation.internal.ValManager$ValidatorCache.getValidatorsCached(ValManager.java:1256)
at org.eclipse.wst.validation.internal.ValManager.getValidators(ValManager.java:197)
at org.eclipse.wst.validation.internal.ValManager.accept(ValManager.java:745)
at org.eclipse.wst.validation.internal.ValBuilderJob.startingValidation(ValBuilderJob.java:148)
at org.eclipse.wst.validation.internal.ValBuilderJob.runInWorkspace(ValBuilderJob.java:122)
at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)