diff --git a/static/js/pandora.js b/static/js/pandora.js
index 4d7c6d952..6cf415773 100644
--- a/static/js/pandora.js
+++ b/static/js/pandora.js
@@ -172,7 +172,7 @@ appPanel
     function loadPandoraFiles(callback) {
         var prefix = '/static/';
         if (localStorage && localStorage['pandora.debug']) {
-            Ox.getJSON(prefix + 'json/pandora.json', function(files) {
+            Ox.getJSON(prefix + 'json/pandora.json?' + Ox.random(1000), function(files) {
                 var promises = [];
                 files.forEach(function(file) {
                     var dfd = new $.Deferred();
@@ -287,7 +287,9 @@ appPanel
             Ox.Request.requests() && pandora.$ui.loadingIcon.start();
             pandora.$ui.body.ajaxStart(pandora.$ui.loadingIcon.start);
             pandora.$ui.body.ajaxStop(pandora.$ui.loadingIcon.stop);
-
+            Ox.Request.bindEvent({
+                error: pandora.ui.errorDialog
+            });
             pandora.site.sectionButtonsWidth = pandora.$ui.sectionButtons.width() + 8;
 
         });
diff --git a/static/js/pandora/errorDialog.js b/static/js/pandora/errorDialog.js
new file mode 100644
index 000000000..7bb035276
--- /dev/null
+++ b/static/js/pandora/errorDialog.js
@@ -0,0 +1,88 @@
+// vim: et:ts=4:sw=4:sts=4:ft=javascript
+'use strict';
+
+pandora.ui.errorDialog = function(data) {
+    var that, error;
+
+    //dont open dialog on unload or if antoher error is open
+    //fixme: error dialog should updated instead
+    if ($('.OxErrorDialog').length || pandora.isUnloading) {
+        return;
+    }
+
+    if (data.status.code == 401 || data.status.code == 403) {
+        that = Ox.Dialog({
+            buttons: [
+                Ox.Button({
+                    id: 'close',
+                    title: 'Close'
+                })
+                .bindEvent({
+                    click: function() {
+                        that.close();
+                    }
+                })
+            ],
+            content: Ox.Element()
+                .append(
+                    $('<img>')
+                        .attr({src: Ox.UI.PATH + 'png/icon128.png'})
+                        .css({position: 'absolute', left: '16px', top: '16px', width: '64px', height: '64px'})
+                )
+                .append(
+                    Ox.Element()
+                        .css({position: 'absolute', left: '96px', top: '16px', width: '256px'})
+                        .html('Sorry, you have made an unauthorized request.')
+                ),
+            fixedSize: true,
+            height: 192,
+            keys: {enter: 'close', escape: 'close'},
+            removeOnClose: true,
+            title: Ox.toTitleCase(data.status.text),
+            width: 368
+        })
+        .open();
+    } else  {
+        // 0 (timeout) or 500 (error)
+        var error = data.status.code == 0 ? 'timeout' : 'error';
+
+        // on window unload, pending request will time out, so
+        // in order to keep the dialog from appearing, delay it
+
+        that = Ox.Dialog({
+            buttons: [
+                Ox.Button({
+                        id: 'close',
+                        title: 'Close'
+                    })
+                    .bindEvent({
+                        click: function() {
+                            that.close();
+                        }
+                    })
+            ],
+            content: Ox.Element()
+                .append(
+                    $('<img>')
+                        .attr({src: Ox.UI.PATH + 'png/icon128.png'})
+                        .css({position: 'absolute', left: '16px', top: '16px', width: '64px', height: '64px'})
+                )
+                .append(
+                    Ox.Element()
+                        .css({position: 'absolute', left: '96px', top: '16px', width: '256px'})
+                        .html(
+                            'Sorry, a server ' + error
+                            + ' occured while handling your request. To help us find out what went wrong, you may want to report this error to an administrator. Otherwise, please try again later.'
+                        )
+                ),
+            fixedSize: true,
+            height: 192,
+            keys: {enter: 'close', escape: 'close'},
+            removeOnClose: true,
+            title: 'Server ' + Ox.toTitleCase(error),
+            width: 368
+        })
+        .open();
+    }
+    that.addClass('OxErrorDialog');
+};
diff --git a/static/js/pandora/utils.js b/static/js/pandora/utils.js
index 8d2a07d45..2881f786e 100644
--- a/static/js/pandora/utils.js
+++ b/static/js/pandora/utils.js
@@ -1034,6 +1034,8 @@ pandora.selectList = function() {
 };
 
 pandora.unloadWindow = function() {
+    //prevent errors on unload
+    pandora.isUnloading = true;
     /*
     // fixme: ajax request has to have async set to false for this to work
     pandora.user.ui.section == 'items'