Treewalker Exception, Eclipse

[jim0205]

I worked on a project using eXistdb. XML Java API, etc. After that anytime I try to create dynamic web prj in eclipse I get this error. When I want to create a new server instance I get this. Please help!!! Or I should completely change my path to a C# programmer using Visual Studio because I am facing this error for a long time. I installed new eclipse, tomcat server it didn't go away!"The selected wizard could not be started.Plug-in "org.eclipse.jst.servlet.ui" was unable to instantiate class "org.eclipse.jst.servlet.ui.project.facet.WebProjectWizard".org/apache/xml/serializer/TreeWalker"Thanks in advanced. NOTE: It is not tomcat's problem, I installed new eclipse, created new workspace, installed new JRE, stil I am able to create a java project, but when I create a class it gives me An internal error occurred during: "Task List Save Job".org/apache/xml/serializer/TreeWalkerThe second error is :Could not save master table to file 'C:\Users\SaraS\Desktop\solve.metadata.plugins\org.eclipse.core.resources.safetable\org.eclipse.core.resources'.C:\Users\SaraS\Desktop\solve.metadata.plugins\org.eclipse.core.resources.safetable\org.eclipse.core.resources (The system cannot find the path specified)Plz note that solve is my workspace name. Help!Update: I installed new JRE, so now I am able to create a dynamic web project then create a class. But when I want to run the tomcat server I again get the first mentioned error!