diff --git a/calendar/inc/class.bocal.inc.php b/calendar/inc/class.bocal.inc.php
index d853257cd4..f0d2042387 100644
--- a/calendar/inc/class.bocal.inc.php
+++ b/calendar/inc/class.bocal.inc.php
@@ -98,6 +98,7 @@ class bocal
 		'R' => 'Rejected',
 		'T' => 'Tentative',
 		'U' => 'No Response',
+		'G' => 'Group invitation',
 	);
 	/**
 	 * @var array recur_types translates MCAL recur-types to verbose labels
@@ -1307,15 +1308,16 @@ class bocal
 	*
 	* @param array $event event-data
 	* @param boolean $long_status=false should the long/verbose status or only the one letter shortcut be used
+	* @param boolean $show_group_invitation=false show group-invitations (status == 'G') or not (default)
 	* @return array with id / names with status pairs
 	*/
-	function participants($event,$long_status=False)
+	function participants($event,$long_status=False,$show_group_invitation=false)
 	{
  		//_debug_array($event);
  		$names = array();
 		foreach($event['participants'] as $id => $status)
 		{
-			if ($status == 'G') continue;	// dont show group-invitation
+			if ($status == 'G' && !$show_group_invitation) continue;	// dont show group-invitation
 
 			$status = $this->verbose_status[$status];
 
diff --git a/calendar/inc/class.bocalupdate.inc.php b/calendar/inc/class.bocalupdate.inc.php
index 893536d562..26fb199fe9 100644
--- a/calendar/inc/class.bocalupdate.inc.php
+++ b/calendar/inc/class.bocalupdate.inc.php
@@ -145,6 +145,7 @@ class bocalupdate extends bocal
 				'end'   => $event['end'],
 				'users' => $users,
 				'ignore_acl' => true,	// otherwise we get only events readable by the user
+				'enum_groups' => true,	// otherwise group-events would not block time
 			));
 			if ($this->debug > 2 || $this->debug == 'update')
 			{
diff --git a/calendar/inc/class.uiforms.inc.php b/calendar/inc/class.uiforms.inc.php
index 5d88220890..f5c157f2ac 100644
--- a/calendar/inc/class.uiforms.inc.php
+++ b/calendar/inc/class.uiforms.inc.php
@@ -767,7 +767,7 @@ class uiforms extends uical
 				'time' => $this->bo->long_date($conflict['start'],$conflict['end'],true),
 				'conflicting_participants' => implode(",\n",$this->bo->participants(array(
 					'participants' => array_intersect_key($conflict['participants'],$event['participants']),
-				))),
+				),true,true)),	// show group invitations too
 				'icon_recur' => $conflict['recur_type'] != MCAL_RECUR_NONE ? 'recur' : '',
 				'text_recur' => $conflict['recur_type'] != MCAL_RECUR_NONE ? lang('Recurring event') : ' ',
 			);		
@@ -971,6 +971,7 @@ class uiforms extends uical
 			'start' => $start,
 			'end'	=> $end,
 			'users'	=> $participants,
+			'ignore_acl' => true,	// otherwise we get only events readable by the user
 		));
 		$busy[] = array(	// add end-of-search-date as event, to cope with empty search and get freetime til that date
 			'start'	=> $end,
diff --git a/calendar/setup/phpgw_de.lang b/calendar/setup/phpgw_de.lang
index c5a7b2cdae..0968f333f8 100644
--- a/calendar/setup/phpgw_de.lang
+++ b/calendar/setup/phpgw_de.lang
@@ -124,6 +124,7 @@ fullname of person to notify	calendar	de	Name der zu benachrichtigenden Person
 general	calendar	de	Allgemein
 global public and group public	calendar	de	Global öffentlich und Gruppen-öffentlich
 global public only	calendar	de	nur Global öffentlich
+group invitation	calendar	de	Gruppeneinladung
 group planner	calendar	de	Gruppenplaner
 group public only	calendar	de	Gruppen-Öffentlich
 groupmember(s) %1 not included, because you have no access.	calendar	de	Gruppenmitglied(er) %1 nicht enthalten, da Sie keinen Zugriff haben.
diff --git a/calendar/setup/phpgw_en.lang b/calendar/setup/phpgw_en.lang
index f630fd3741..d8b19b5a32 100644
--- a/calendar/setup/phpgw_en.lang
+++ b/calendar/setup/phpgw_en.lang
@@ -124,6 +124,7 @@ fullname of person to notify	calendar	en	Fullname of person to notify
 general	calendar	en	General
 global public and group public	calendar	en	global public and group public
 global public only	calendar	en	global public only
+group invitation	calendar	en	Group invitation
 group planner	calendar	en	Group planner
 group public only	calendar	en	group public only
 groupmember(s) %1 not included, because you have no access.	calendar	en	Groupmember(s) %1 not included, because you have no access.