diff --git a/plugins/relaxng/src/org/intellij/plugins/relaxNG/references/PrefixReferenceProvider.java b/plugins/relaxng/src/org/intellij/plugins/relaxNG/references/PrefixReferenceProvider.java
index ee5354b8515f..6252728de819 100644
--- a/plugins/relaxng/src/org/intellij/plugins/relaxNG/references/PrefixReferenceProvider.java
+++ b/plugins/relaxng/src/org/intellij/plugins/relaxNG/references/PrefixReferenceProvider.java
@@ -22,6 +22,7 @@ import com.intellij.codeInsight.daemon.impl.HighlightInfo;
 import com.intellij.codeInsight.daemon.impl.analysis.CreateNSDeclarationIntentionFix;
 import com.intellij.codeInsight.daemon.impl.quickfix.QuickFixAction;
 import com.intellij.lang.xml.XMLLanguage;
+import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.util.TextRange;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiReference;
@@ -44,6 +45,8 @@ import org.jetbrains.annotations.Nullable;
 * Date: 24.07.2007
 */
 public class PrefixReferenceProvider extends PsiReferenceProviderBase {
+  private static final Logger LOG = Logger.getInstance("#org.intellij.plugins.relaxNG.references.PrefixReferenceProvider");
+
   @NotNull
   public PsiReference[] getReferencesByElement(@NotNull PsiElement element, @NotNull ProcessingContext context) {
     final XmlAttributeValue value = (XmlAttributeValue)element;
@@ -102,7 +105,7 @@ public class PrefixReferenceProvider extends PsiReferenceProviderBase {
         QuickFixAction.registerQuickFixAction(info,
               new CreateNSDeclarationIntentionFix(tag, reference.getCanonicalText()));
       } catch (Throwable e) {
-        e.printStackTrace();
+        LOG.error(e);
       }
     }
 
diff --git a/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/MessageViewHelper.java b/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/MessageViewHelper.java
index a0af4a70dd45..a2baae294ffc 100644
--- a/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/MessageViewHelper.java
+++ b/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/MessageViewHelper.java
@@ -17,7 +17,9 @@
 package org.intellij.plugins.relaxNG.validation;
 
 import com.intellij.ide.errorTreeView.NewErrorTreeViewPanel;
+import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.command.CommandProcessor;
+import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.ui.Messages;
 import com.intellij.openapi.util.Key;
@@ -33,7 +35,6 @@ import org.xml.sax.SAXException;
 import org.xml.sax.SAXParseException;
 import org.xml.sax.helpers.DefaultHandler;
 
-import javax.swing.*;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.util.Set;
@@ -44,6 +45,8 @@ import java.util.Set;
  * Date: 19.11.2007
  */
 public class MessageViewHelper {
+  private static final Logger LOG = Logger.getInstance("#org.intellij.plugins.relaxNG.validation.MessageViewHelper");
+
   private final Project myProject;
 
   private final Set<String> myErrors = new THashSet<String>();
@@ -91,23 +94,23 @@ public class MessageViewHelper {
       try {
         file = VfsUtil.findFileByURL(new URL(systemId));
       } catch (MalformedURLException e) {
-        System.err.println("systemId = " + systemId);
-        e.printStackTrace();
+        LOG.warn("systemId = " + systemId);
+        LOG.error(e);
       }
     }
 
     final VirtualFile file1 = file;
-    SwingUtilities.invokeLater(
-            new Runnable() {
-              public void run() {
-                myErrorsView.addMessage(
-                        warning ? MessageCategory.WARNING : MessageCategory.ERROR,
-                        new String[]{ ex.getLocalizedMessage() },
-                        file1,
-                        ex.getLineNumber() - 1,
-                        ex.getColumnNumber() - 1, null);
-              }
-            }
+    ApplicationManager.getApplication().invokeLater(
+      new Runnable() {
+        public void run() {
+          myErrorsView.addMessage(
+            warning ? MessageCategory.WARNING : MessageCategory.ERROR,
+            new String[]{ex.getLocalizedMessage()},
+            file1,
+            ex.getLineNumber() - 1,
+            ex.getColumnNumber() - 1, null);
+        }
+      }
     );
   }
 
diff --git a/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/RngParser.java b/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/RngParser.java
index 2e41399879ca..232938704cd1 100644
--- a/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/RngParser.java
+++ b/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/RngParser.java
@@ -16,6 +16,7 @@
 
 package org.intellij.plugins.relaxNG.validation;
 
+import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.util.Key;
 import com.intellij.openapi.util.SystemInfo;
@@ -62,12 +63,15 @@ import java.io.StringReader;
 * Date: 19.07.2007
 */
 public class RngParser {
+  private static final Logger LOG = Logger.getInstance("#org.intellij.plugins.relaxNG.validation.RngParser");
+
   static final Key<CachedValue<Schema>> SCHEMA_KEY = Key.create("SCHEMA");
   static final Key<CachedValue<DPattern>> PATTERN_KEY = Key.create("PATTERN");
 
   public static final DefaultHandler DEFAULT_HANDLER = new DefaultHandler() {
     public void error(SAXParseException e) throws SAXException {
-      System.out.println("e.getMessage() = " + e.getMessage() + " [" + e.getSystemId() + "]");
+      LOG.info("e.getMessage() = " + e.getMessage() + " [" + e.getSystemId() + "]");
+      LOG.info(e);
     }
   };
 
@@ -90,9 +94,9 @@ public class RngParser {
 
       return (DPattern)p.parse(checking ? new CheckingSchemaBuilder(sb, eh) : sb);
     } catch (BuildException e) {
-      e.printStackTrace();
+      LOG.info(e);
     } catch (IllegalSchemaException e) {
-      System.out.println("invalid schema: " + file.getVirtualFile().getPresentableUrl());
+      LOG.info("invalid schema: " + file.getVirtualFile().getPresentableUrl());
     }
     return null;
   }
@@ -166,7 +170,7 @@ public class RngParser {
               return Result.createSingleDependency(schema, descriptorFile);
             }
           } catch (Exception e) {
-            e.printStackTrace();
+            LOG.info(e);
             return Result.createSingleDependency(null, descriptorFile);
           }
         }
diff --git a/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/XmlInstanceValidator.java b/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/XmlInstanceValidator.java
index 2956996170f3..02a835452697 100644
--- a/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/XmlInstanceValidator.java
+++ b/plugins/relaxng/src/org/intellij/plugins/relaxNG/validation/XmlInstanceValidator.java
@@ -17,6 +17,7 @@
 package org.intellij.plugins.relaxNG.validation;
 
 import com.intellij.codeInsight.daemon.Validator;
+import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.progress.ProcessCanceledException;
 import com.intellij.psi.PsiDocumentManager;
@@ -40,6 +41,7 @@ import org.xml.sax.SAXParseException;
  * Date: 30.07.2007
  */
 public class XmlInstanceValidator {
+  private static final Logger LOG = Logger.getInstance("#org.intellij.plugins.relaxNG.validation.MessageViewHelper");
 
   public static void doValidation(@NotNull final XmlDocument doc, final Validator.ValidationHost host, final XmlFile descriptorFile) {
     try {
@@ -61,9 +63,11 @@ public class XmlInstanceValidator {
       doc.accept(new Psi2SaxAdapter(handler));
 
     } catch (ProcessCanceledException e) {
-      throw e;
+      LOG.error(e);
+    } catch (RuntimeException e) {
+      LOG.error(e);
     } catch (Exception e) {
-      e.printStackTrace();
+      LOG.info(e);
     }
   }
 
diff --git a/plugins/relaxng/test/org/intellij/plugins/relaxNG/HighlightingTestBase.java b/plugins/relaxng/test/org/intellij/plugins/relaxNG/HighlightingTestBase.java
index a25cff996b95..08dc74d42a96 100644
--- a/plugins/relaxng/test/org/intellij/plugins/relaxNG/HighlightingTestBase.java
+++ b/plugins/relaxng/test/org/intellij/plugins/relaxNG/HighlightingTestBase.java
@@ -85,7 +85,7 @@ public abstract class HighlightingTestBase extends TestCase implements IdeaCodeI
         }
       });
     } catch (IOException e) {
-      e.printStackTrace();
+      throw new RuntimeException(e);
     }
   }