diff --git a/events.py b/events.py
index 13f122f..a00cf63 100644
--- a/events.py
+++ b/events.py
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+import logging
 import time
 import sched
 import threading
@@ -8,7 +9,7 @@ EVENTLOOP_DELAY = 0.100  # seconds
 event_list = sched.scheduler(time.time, time.sleep)
 
 
-def register_active_event(t, callback, args, action_runner, plugin, msg_obj):
+def register_active_event(t, callback, args, action_runner, plugin, msg_obj, mutex=None):
     """
     Execute a callback at a given time and react on the output
 
@@ -24,10 +25,14 @@ def register_active_event(t, callback, args, action_runner, plugin, msg_obj):
         action = callback(*func_args)
         if action:
             action_runner(action=action, plugin=plugin, msg_obj=msg_obj)
-    event_list.enterabs(t, 0, func, args)
+    register_event(t, func, args, mutex=mutex)
 
 
-def register_event(t, callback, args):
+def register_event(t, callback, args, **kwargs):
+    for pending_event in event_list.queue:
+        if kwargs.get('mutex') and pending_event.kwargs.get('mutex', None) == kwargs.get('mutex'):
+            logging.debug("Dropped event: %s", kwargs.get('mutex'))
+            return
     event_list.enterabs(t, 0, callback, args)
 
 
diff --git a/plugins/commands.py b/plugins/commands.py
index 5bd51f7..90882d6 100644
--- a/plugins/commands.py
+++ b/plugins/commands.py
@@ -363,7 +363,8 @@ def command_teatimer(argv, **args):
         ),
         'event': {
             'time': ready,
-            'msg': (args['reply_user'] + ': Your tea is ready!')
+            'msg': (args['reply_user'] + ': Your tea is ready!'),
+            'mutex': 'teatimer_{}'.format(args['reply_user'])
         }
     }
 
@@ -629,9 +630,11 @@ def command_dsa_watcher(argv=None, **_):
     msg = 'next crawl set to %s' % time.strftime('%Y-%m-%d %H:%M', time.localtime(crawl_at))
     out.append(msg)
     return {
+        # 'msg': out,
         'event': {
             'time': crawl_at,
-            'command': (command_dsa_watcher, ([],))
+            'command': (command_dsa_watcher, ([],)),
+            'mutex': 'dsa'
         }
     }
 
diff --git a/urlbot.py b/urlbot.py
index 96ec0d3..833bc7c 100755
--- a/urlbot.py
+++ b/urlbot.py
@@ -12,7 +12,9 @@ from collections import deque
 from lxml import etree
 
 import requests
+from sleekxmpp.plugins import PluginNotFound
 
+import plugins  # force initialization
 from plugin_system import plugin_storage, ptypes, plugin_enabled_get
 from rate_limit import rate_limit_classes, RATE_GLOBAL, RATE_CHAT, RATE_EVENT, rate_limit
 
@@ -44,6 +46,9 @@ class UrlBot(IdleBot):
         for room in self.rooms:
             self.add_event_handler('muc::%s::got_online' % room, self.muc_online)
 
+        dsa_plugin = list(filter(lambda x: x.plugin_name == 'dsa-watcher', plugin_storage[ptypes.COMMAND]))[0]
+        self._run_action(dsa_plugin(), dsa_plugin, None)
+
     def muc_message(self, msg_obj):
         """
         Handle muc messages, return if irrelevant content or die by hangup.
@@ -109,7 +114,10 @@ class UrlBot(IdleBot):
             other_bots = config.runtimeconf_get("other_bots")
             if not other_bots:
                 return False
-            users = self.plugin['xep_0045'].getRoster(room)
+            try:
+                users = self.plugin['xep_0045'].getRoster(room)
+            except PluginNotFound:
+                users = []
             return set(users).intersection(set(other_bots))
 
         def _prevent_panic(message, room):
@@ -349,7 +357,8 @@ class UrlBot(IdleBot):
                         args=command[1],
                         action_runner=self._run_action,
                         plugin=plugin,
-                        msg_obj=msg_obj
+                        msg_obj=msg_obj,
+                        mutex=event.get('mutex')
                     )
 
         if 'msg' in action and rate_limit(RATE_CHAT | plugin.ratelimit_class):