diff --git a/core/org.eclipse.cdt.core/ChangeLog b/core/org.eclipse.cdt.core/ChangeLog
index 56c4b320c85..b838cef8c0c 100644
--- a/core/org.eclipse.cdt.core/ChangeLog
+++ b/core/org.eclipse.cdt.core/ChangeLog
@@ -1,3 +1,11 @@
+2004-04-19 Alain Magloire
+
+	Fix for PR 59098
+
+	* model/org/eclipse/cdt/internal/core/model/CModel.java
+	* model/org/eclipse/cdt/internal/core/model/CProjectInfo.java
+	* model/org/eclipse/cdt/internal/core/model/DeltaProcessor.java
+
 2004-04-19 Alain Magloire
 
 	It has become necessary to add exception in the interface
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CModel.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CModel.java
index db07e80a876..13831906e66 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CModel.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CModel.java
@@ -74,6 +74,25 @@ public class CModel extends Openable implements ICModel {
 		}
 	}
 
+	/**
+	 * Finds the given project in the list of the java model's children.
+	 * Returns null if not found.
+	 */
+	public ICProject findCProject(IProject project) {
+		try {
+			ICProject[] projects = getOldCProjectsList();
+			for (int i = 0, length = projects.length; i < length; i++) {
+				ICProject javaProject = projects[i];
+				if (project.equals(javaProject.getProject())) {
+					return javaProject;
+				}
+			}
+		} catch (CModelException e) {
+			// c model doesn't exist: cannot find any project
+		}
+		return null;
+	}
+	
 	public IWorkspace getWorkspace() {
 		return getUnderlyingResource().getWorkspace();
 	}
@@ -141,6 +160,18 @@ public class CModel extends Openable implements ICModel {
 		return resource.hashCode();
 	}
 
+	/**
+	 * Workaround for bug 15168 circular errors not reported
+	 * Returns the list of java projects before resource delta processing
+	 * has started.
+	 */
+	public ICProject[] getOldCProjectsList() throws CModelException {
+		CModelManager manager = CModelManager.getDefault();
+		return manager.cProjectsCache == null ?
+				getCProjects() :
+				manager.cProjectsCache;
+	}
+
 	/* (non-Javadoc)
 	 * @see org.eclipse.cdt.internal.core.model.Openable#generateInfos(org.eclipse.cdt.internal.core.model.OpenableInfo, org.eclipse.core.runtime.IProgressMonitor, java.util.Map, org.eclipse.core.resources.IResource)
 	 */
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CProjectInfo.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CProjectInfo.java
index 39e2daede98..e56bfc0a119 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CProjectInfo.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CProjectInfo.java
@@ -18,7 +18,6 @@ import org.eclipse.cdt.core.model.ISourceRoot;
 import org.eclipse.core.resources.IContainer;
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.runtime.CoreException;
-import org.eclipse.core.runtime.IPath;
 
 /** 
  * Info for ICProject.
@@ -64,9 +63,7 @@ class CProjectInfo extends OpenableInfo {
 		if (nonCResources != null)
 			return nonCResources;
 
-		CProject cproject = (CProject)getElement();
 		// determine if src == project
-		IPath projectPath = res.getProject().getFullPath();
 		ISourceRoot root = null;
 		ICElement[] elements = getChildren();
 		for (int i = 0; i < elements.length; i++) {
@@ -80,7 +77,6 @@ class CProjectInfo extends OpenableInfo {
 		}
 
 		ArrayList notChildren = new ArrayList();
-		ICElement parent = getElement();
 		try {
 			IResource[] resources = null;
 			if (res instanceof IContainer) {
@@ -89,7 +85,6 @@ class CProjectInfo extends OpenableInfo {
 			}
 
 			if (resources != null) {
-				CModelManager factory = CModelManager.getDefault();
 				ICElement[] children;
 				if (root == null) {
 					children = getChildren();
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/DeltaProcessor.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/DeltaProcessor.java
index 36002542050..82a0816d087 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/DeltaProcessor.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/DeltaProcessor.java
@@ -525,8 +525,22 @@ public class DeltaProcessor {
 						}
 					} 
 					if ((flags & IResourceDelta.DESCRIPTION) != 0) {
-						if (element != null) {
-							elementAdded(element, delta);
+						IProject res = (IProject)delta.getResource();
+						CModel cModel = CModelManager.getDefault().getCModel();
+						boolean wasCProject = cModel.findCProject(res) != null;
+						boolean isCProject = CProject.hasCNature(res);
+						if (wasCProject != isCProject) {
+							// project's nature has been added or removed
+							if (element != null) {
+								// note its resources are still visible as roots to other projects
+								if (isCProject) {
+									elementAdded(element, delta);
+									updateIndexAddResource(element, delta);
+								} else {
+									elementRemoved(element, delta);
+									updateIndexRemoveResource(element, delta);
+								}
+							}
 						}
 					}
 				}