[251542] Closing a project causes errors in the log
diff --git a/plugins/org.eclipse.wst.validation/validate/org/eclipse/wst/validation/internal/ProjectConfiguration.java b/plugins/org.eclipse.wst.validation/validate/org/eclipse/wst/validation/internal/ProjectConfiguration.java
index 63407bf..fe0c9c0 100644
--- a/plugins/org.eclipse.wst.validation/validate/org/eclipse/wst/validation/internal/ProjectConfiguration.java
+++ b/plugins/org.eclipse.wst.validation/validate/org/eclipse/wst/validation/internal/ProjectConfiguration.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2001, 2008 IBM Corporation and others.
+ * Copyright (c) 2001, 2009 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -598,7 +598,9 @@
 				pref.put(ValidationConfiguration.DelegatesPreference, serializeDelegatesSetting());
 				pref.flush();
 			} catch (BackingStoreException e) {
-				ValidationPlugin.getPlugin().handleException(e);
+				// A common error is that the project has been closed, in which case there
+				// is nothing that we can do.
+				if (project.isAccessible())ValidationPlugin.getPlugin().handleException(e);
 			}
 		}
 	}
diff --git a/plugins/org.eclipse.wst.validation/validate/org/eclipse/wst/validation/internal/operations/ValidationBuilder.java b/plugins/org.eclipse.wst.validation/validate/org/eclipse/wst/validation/internal/operations/ValidationBuilder.java
index 61666ed..824aace 100644
--- a/plugins/org.eclipse.wst.validation/validate/org/eclipse/wst/validation/internal/operations/ValidationBuilder.java
+++ b/plugins/org.eclipse.wst.validation/validate/org/eclipse/wst/validation/internal/operations/ValidationBuilder.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2001, 2008 IBM Corporation and others.
+ * Copyright (c) 2001, 2009 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -173,9 +173,10 @@
 				performFullBuild(monitor, prjp);
 			} else {
 				if (delta.getAffectedChildren().length == 0) {
-					if (isReferencedProjectInDelta(referenced))
+					if (isReferencedProjectInDelta(referenced)){
 						cleanupReferencedProjectsMarkers(prjp, referenced);
 						performFullBuildForReferencedProjectChanged(monitor, prjp);
+					}
 					return referenced;
 				}
 				EnabledIncrementalValidatorsOperation operation = new EnabledIncrementalValidatorsOperation(project, delta, true);
@@ -212,7 +213,7 @@
 			Set<ValidatorMetaData>  set = new HashSet<ValidatorMetaData>();
 			set.addAll( Arrays.asList( enabledValidators ) );
 			for (IProject p : referenced) {
-				if (!p.exists())continue;
+				if (!p.isAccessible())continue;
 				ProjectConfiguration refProjectCfg = ConfigurationManager.getManager().getProjectConfiguration(p);
 		
 				ValidatorMetaData[] refEnabledValidators = refProjectCfg.getEnabledFullBuildValidators(true, false);