Index: base.py
===================================================================
--- base.py	(revision 10658)
+++ base.py	(working copy)
@@ -368,7 +368,11 @@
         assert callable(_f), "%s is not callable" % _f
         assert sys.maxint >= _seconds >= 0, \
                "%s is not greater than or equal to 0 seconds" % 
(_seconds,)
-        tple = DelayedCall(seconds() + _seconds, _f, args, kw,
+        if _seconds == 0:
+            tcc = 0
+        else:
+            tcc = seconds() + _seconds
+        tple = DelayedCall(tcc, _f, args, kw,
                            self._pendingTimedCalls.remove,
                            self._resetCallLater)
         insort(self._pendingTimedCalls, tple)
@@ -416,8 +420,11 @@
                 count += 1
             del self.threadCallQueue[:count]
         now = seconds()
-        while self._pendingTimedCalls and (self._pendingTimedCalls[-1].time <= now):
-            call = self._pendingTimedCalls.pop()
+        do=[]
+        while self._pendingTimedCalls and (self._pendingTimedCalls[-1].time <= now):
+            do.append(self._pendingTimedCalls.pop())
+        for call in do:
             try:
                 call.called = 1
                 call.func(*call.args, **call.kw)