diff --git a/source/java/org/alfresco/web/forms/xforms/XFormsBean.java b/source/java/org/alfresco/web/forms/xforms/XFormsBean.java
index 09c1e4f157..b27ac90a36 100644
--- a/source/java/org/alfresco/web/forms/xforms/XFormsBean.java
+++ b/source/java/org/alfresco/web/forms/xforms/XFormsBean.java
@@ -283,7 +283,7 @@ public class XFormsBean
     * Writes the xform out to the http servlet response.  This allows
     * us to use the browser to parse the xform using XMLHttpRequest.
     */
-   public void getXForm() 
+   public synchronized void getXForm() 
       throws IOException,
       XFormsException
    {
@@ -302,7 +302,7 @@ public class XFormsBean
     * @param value the new value
     * @return the list of events that may result through this action
     */
-   public void setXFormsValue() 
+   public synchronized void setXFormsValue() 
       throws XFormsException, IOException
    {
       final FacesContext context = FacesContext.getCurrentInstance();
@@ -357,7 +357,7 @@ public class XFormsBean
     *
     * @param id the id of the control in the host document
     */
-   public void fireAction() 
+   public synchronized void fireAction() 
       throws XFormsException, IOException
    {
       final FacesContext context = FacesContext.getCurrentInstance();
@@ -376,7 +376,7 @@ public class XFormsBean
    /**
     * handles submits and sets the instance data.
     */
-   public void handleAction() 
+   public synchronized void handleAction() 
    {
       LOGGER.debug(this + ".handleAction");
       try
@@ -410,7 +410,7 @@ public class XFormsBean
    /**
     * Swaps model nodes to implement reordering within repeats.
     */
-   public void swapRepeatItems() 
+   public synchronized void swapRepeatItems() 
       throws Exception
    {
       final FacesContext context = FacesContext.getCurrentInstance();
@@ -420,8 +420,17 @@ public class XFormsBean
       final String toItemId = (String)requestParameters.get("toItemId");
       LOGGER.debug(this + ".swapRepeatItems(" + fromItemId + ", " + toItemId + ")");
       final ChibaBean chibaBean = this.xformsSession.chibaBean;
-      this.swapRepeatItems((RepeatItem)chibaBean.getContainer().lookup(fromItemId), 
-                           (RepeatItem)chibaBean.getContainer().lookup(toItemId));
+      final RepeatItem from = (RepeatItem)chibaBean.getContainer().lookup(fromItemId);
+      if (from == null)
+      {
+         throw new NullPointerException("unable to find source repeat item " + fromItemId);
+      }
+      final RepeatItem to = (RepeatItem)chibaBean.getContainer().lookup(toItemId);
+      if (to == null)
+      {
+         throw new NullPointerException("unable to find destination repeat item " + toItemId);
+      }
+      this.swapRepeatItems(from, to);
 
       final ResponseWriter out = context.getResponseWriter();
       XMLUtil.print(this.getEventLog(), out);
diff --git a/source/web/scripts/ajax/xforms.js b/source/web/scripts/ajax/xforms.js
index ffe82c45d3..51b420ad9f 100644
--- a/source/web/scripts/ajax/xforms.js
+++ b/source/web/scripts/ajax/xforms.js
@@ -2352,6 +2352,7 @@ dojo.declare("alfresco.xforms.Repeat",
              {
                this.repeatControls = [];
                this._selectedIndex = -1;
+               this._locked = false;
              },
              {
                /////////////////////////////////////////////////////////////////
@@ -2727,13 +2728,14 @@ dojo.declare("alfresco.xforms.Repeat",
                {
                  dojo.event.browser.stopEvent(event);
                  var repeat = event.target.repeat;
-                 if (repeat.isInsertRepeatItemEnabled())
+                 if (!repeat._locked && repeat.isInsertRepeatItemEnabled())
                  {
                    var index = repeat.repeatControls.indexOf(event.target.parentNode);
                    var repeatItem = repeat.getChildAt(index);
                    this.setFocusedChild(repeatItem);
                    var trigger = this._getRepeatItemTrigger("insert", { position: "after" });
                    trigger.fire();
+                   repeat._locked = true;
                  }
                },
 
@@ -2747,11 +2749,12 @@ dojo.declare("alfresco.xforms.Repeat",
                  {
                    dojo.event.browser.stopEvent(event);
                    var repeat = event.target.repeat;
-                   if (repeat.isInsertRepeatItemEnabled())
+                   if (!repeat._locked && repeat.isInsertRepeatItemEnabled())
                    {
                      this.setFocusedChild(null);
                      var trigger = this._getRepeatItemTrigger("insert", { position: "before" });
                      trigger.fire();
+                     repeat._locked = true;
                    }
                  }
                },
@@ -2764,13 +2767,14 @@ dojo.declare("alfresco.xforms.Repeat",
                {
                  dojo.event.browser.stopEvent(event);
                  var repeat = event.target.repeat;
-                 if (repeat.isRemoveRepeatItemEnabled())
+                 if (!repeat._locked && repeat.isRemoveRepeatItemEnabled())
                  {
                    var index = repeat.repeatControls.indexOf(event.target.parentNode);
                    var repeatItem = repeat.getChildAt(index);
                    this.setFocusedChild(repeatItem);
                    var trigger = this._getRepeatItemTrigger("delete", {});
                    trigger.fire();
+                   repeat._locked = true;
                  }
                },
 
@@ -2783,11 +2787,12 @@ dojo.declare("alfresco.xforms.Repeat",
                  dojo.event.browser.stopEvent(event);
                  var repeat = event.target.repeat;
                  var index = repeat.repeatControls.indexOf(event.target.parentNode);
-                 if (index != 0 && repeat._children.length != 1)
+                 if (!repeat._locked && index != 0 && repeat._children.length != 1)
                  {
                    var repeatItem = repeat.getChildAt(index);
                    this.setFocusedChild(repeatItem);
                    repeat._swapChildren(index, index - 1);
+                   repeat._locked = true;
                  }
                },
 
@@ -2800,11 +2805,12 @@ dojo.declare("alfresco.xforms.Repeat",
                  dojo.event.browser.stopEvent(event);
                  var repeat = event.target.repeat;
                  var index = repeat.repeatControls.indexOf(event.target.parentNode);
-                 if (index != repeat._children.length - 1 && repeat._children.length != 1)
+                 if (!repeat._locked && index != repeat._children.length - 1 && repeat._children.length != 1)
                  {
                    var repeatItem = repeat.getChildAt(index);
                    this.setFocusedChild(repeatItem);
                    repeat._swapChildren(index, index + 1);
+                   repeat._locked = true;
                  }
                },
 
@@ -2847,6 +2853,7 @@ dojo.declare("alfresco.xforms.Repeat",
                  var w = this.xform.createWidget(clonedPrototype);
                  this._insertChildAt(w, position);
                  this.xform.loadWidgets(w.xformsNode, w);
+                 this._locked = false;
                },
 
                /** Deletes the item at the specified position. */
@@ -2854,6 +2861,7 @@ dojo.declare("alfresco.xforms.Repeat",
                {
                  dojo.debug(this.id + ".handleItemDeleted(" + position + ")");
                  this._removeChildAt(position);
+                 this._locked = false;
                }
              });