diff --git a/UI/WebServerResources/UIxAppointmentEditor.js b/UI/WebServerResources/UIxAppointmentEditor.js
index 5a905c179..1e053f2fb 100644
--- a/UI/WebServerResources/UIxAppointmentEditor.js
+++ b/UI/WebServerResources/UIxAppointmentEditor.js
@@ -55,7 +55,8 @@ function validateAptEditor() {
         alert(labels.validate_invalid_startdate);
         return false;
     }
-    startdate = e.calendar.prs_date(e.value);
+
+    startdate = getStartDate();
     if (startdate == null) {
         alert(labels.validate_invalid_startdate);
         return false;
@@ -66,7 +67,7 @@ function validateAptEditor() {
         alert(labels.validate_invalid_enddate);
         return false;
     }
-    enddate = e.calendar.prs_date(e.value);
+    enddate = getEndDate();
     if (enddate == null) {
         alert(labels.validate_invalid_enddate);
         return false;
@@ -235,6 +236,9 @@ function _getDate(which) {
         date.setMinutes(time[2]);
     }
 
+    if (isNaN(date.getTime()))
+        return null;
+
     return date;
 }
 
@@ -290,35 +294,47 @@ function onAdjustTime(event) {
   
     if ($(this).readAttribute("id").startsWith("start")) {
         // Start date was changed
-        var delta = window.getShadowStartDate().valueOf() - startDate.valueOf();
-        window.setStartDate();
-        if (delta != 0) {
-            var newEndDate = new Date(endDate.valueOf() - delta);
-            window.setEndDate(newEndDate);
+        if (startDate == null) {
+            var oldStartDate = window.getShadowStartDate();
+            window.setStartDate(oldStartDate);
+        }
+        else {
+            var delta = window.getShadowStartDate().valueOf() - startDate.valueOf();
             window.setStartDate();
+            if (delta != 0) {
+                // Increment end date
+                var newEndDate = new Date(endDate.valueOf() - delta);
+                window.setEndDate(newEndDate);
     
-            window.timeWidgets['end']['date'].updateShadowValue();
-            window.timeWidgets['end']['time'].updateShadowValue();
-            window.timeWidgets['start']['date'].updateShadowValue();
-            window.timeWidgets['start']['time'].updateShadowValue();
-            if (window.timeWidgets['end']['time'].onChange)
-                window.timeWidgets['end']['time'].onChange(); // method from SOGoTimePicker
+                window.timeWidgets['end']['date'].updateShadowValue();
+                window.timeWidgets['end']['time'].updateShadowValue();
+                window.timeWidgets['start']['date'].updateShadowValue();
+                window.timeWidgets['start']['time'].updateShadowValue();
+                if (window.timeWidgets['end']['time'].onChange)
+                    window.timeWidgets['end']['time'].onChange(); // method from SOGoTimePicker
+            }
         }
     }
     else {
         // End date was changed
-        var delta = endDate.valueOf() - startDate.valueOf();
-        if (delta < 0) {
-            alert(labels.validate_endbeforestart);
+        if (endDate == null) {
             var oldEndDate = window.getShadowEndDate();
             window.setEndDate(oldEndDate);
-
-            window.timeWidgets['end']['date'].updateShadowValue();
-            window.timeWidgets['end']['time'].updateShadowValue();
-            window.timeWidgets['end']['time'].onChange(); // method from SOGoTimePicker
         }
         else {
-            window.setEndDate();
+            var delta = endDate.valueOf() - startDate.valueOf();
+            if (delta < 0) {
+                alert(labels.validate_endbeforestart);
+                var oldEndDate = window.getShadowEndDate();
+                window.setEndDate(oldEndDate);
+
+                window.timeWidgets['end']['date'].updateShadowValue();
+                window.timeWidgets['end']['time'].updateShadowValue();
+                window.timeWidgets['end']['time'].onChange(); // method from SOGoTimePicker
+            }
+            else {
+                window.setEndDate();
+            }
         }
     }
 }
diff --git a/UI/WebServerResources/UIxPreferences.js b/UI/WebServerResources/UIxPreferences.js
index fad9612a9..16f560f26 100644
--- a/UI/WebServerResources/UIxPreferences.js
+++ b/UI/WebServerResources/UIxPreferences.js
@@ -51,9 +51,9 @@ function savePreferences(sender) {
 	}
         if ($("enableVacationEndDate") && $("enableVacationEndDate").checked) {
             var e = $("vacationEndDate_date");
-            var endDate = e.calendar.prs_date(e.value);
+            var endDate = e.inputAsDate();
             var now = new Date();
-            if (endDate.getTime() < now.getTime()) {
+            if (isNaN(endDate.getTime()) || endDate.getTime() < now.getTime()) {
                 showAlertDialog(_("End date of your auto reply must be in the future."));
                 sendForm = false;
             }
diff --git a/UI/WebServerResources/UIxTaskEditor.js b/UI/WebServerResources/UIxTaskEditor.js
index 2c89ee54a..5a0351937 100644
--- a/UI/WebServerResources/UIxTaskEditor.js
+++ b/UI/WebServerResources/UIxTaskEditor.js
@@ -18,11 +18,11 @@ function uixEarlierDate(date1, date2) {
   return null;
 }
 
-function validateDate(date, label) {
+function validateDate(which, label) {
   var result, dateValue;
 
-  dateValue = date.calendar.prs_date(date.value);
-  if (date.value.length != 10 || !dateValue) {
+  dateValue = this._getDate(which);
+  if (dateValue == null) {
     alert(label);
     result = false;
   } else
@@ -41,14 +41,14 @@ function validateTaskEditor() {
 
   e = document.getElementById('startTime_date');
   if (!e.disabled) {
-    startdate = validateDate(e, labels.validate_invalid_startdate);
+    startdate = validateDate('start', labels.validate_invalid_startdate);
     if (!startdate)
       return false;
   }
 
   e = document.getElementById('dueTime_date');
   if (!e.disabled) {
-    enddate = validateDate(e, labels.validate_invalid_enddate);
+    enddate = validateDate('due', labels.validate_invalid_enddate);
     if (!enddate)
       return false;
   }
@@ -204,6 +204,9 @@ this._getDate = function(which) {
         date.setHours(time[0]);
         date.setMinutes(time[1]);
 
+        if (isNaN(date.getTime()))
+            return null;
+
 	return date;
 };
 
@@ -235,6 +238,11 @@ this.getShadowDueDate = function() {
 this._setDate = function(which, newDate) {
 	window.timeWidgets[which]['date'].setInputAsDate(newDate);
         window.timeWidgets[which]['time'].value = newDate.getDisplayHoursString();
+
+        // Update date picker
+        var dateComponent = jQuery(window.timeWidgets[which]['date']).closest('.date');
+        dateComponent.data('date', window.timeWidgets[which]['date'].value);
+        dateComponent.datepicker('update');
 };
 
 this.setStartDate = function(newStartDate) {
@@ -242,7 +250,6 @@ this.setStartDate = function(newStartDate) {
 };
 
 this.setDueDate = function(newDueDate) {
-	//   window.alert(newDueDate);
 	this._setDate('due', newDueDate);
 };
 
@@ -268,8 +275,8 @@ this.initTimeWidgets = function (widgets) {
         jQuery(widgets['due']['date']).closest('.date').datepicker({autoclose: true});
         jQuery('#statusTime_date').closest('.date').datepicker({autoclose: true});
 
-	widgets['start']['date'].observe("change", this.onAdjustDueTime, false);
-	widgets['start']['time'].observe("time:change", this.onAdjustDueTime, false);
+        jQuery(widgets['start']['date']).change(onAdjustTime);
+	widgets['start']['time'].on("time:change", onAdjustDueTime);
         widgets['start']['time'].addInterface(SOGoTimePickerInterface);
         widgets['due']['time'].addInterface(SOGoTimePickerInterface);
 };