diff --git a/rattail_tempmon/server.py b/rattail_tempmon/server.py
index 34c4a24..58808f8 100644
--- a/rattail_tempmon/server.py
+++ b/rattail_tempmon/server.py
@@ -63,7 +63,8 @@ class TempmonServerDaemon(Daemon):
 
         try:
             clients = session.query(tempmon.Client)\
-                             .filter(tempmon.Client.enabled == True)
+                             .filter(tempmon.Client.enabled == True)\
+                             .filter(tempmon.Client.archived == False)
             for client in clients:
                 self.check_readings_for_client(session, client)
         except:
@@ -75,11 +76,18 @@ class TempmonServerDaemon(Daemon):
             session.close()
 
     def check_readings_for_client(self, session, client):
+        """
+        Check readings for all (enabled) probes for the given client.
+        """
+        # cutoff is calculated as the client delay (i.e. how often it takes
+        # readings) plus one minute.  we "should" have a reading for each probe
+        # within that time window.  if no readings are found we will consider
+        # the client to be (possibly) offline.
         delay = client.delay or 60
         cutoff = self.now - datetime.timedelta(seconds=delay + 60)
-        online = True
+        online = False
         for probe in client.enabled_probes():
-            online = online and bool(self.check_readings_for_probe(session, probe, cutoff))
+            online = online or bool(self.check_readings_for_probe(session, probe, cutoff))
 
         # if client was previously marked online, but we have no "new"
         # readings, then let's look closer to see if it's been long enough to
@@ -103,31 +111,39 @@ class TempmonServerDaemon(Daemon):
 
 
     def check_readings_for_probe(self, session, probe, cutoff):
-        readings = session.query(tempmon.Reading)\
-                          .filter(tempmon.Reading.probe == probe)\
-                          .filter(tempmon.Reading.taken >= cutoff)\
-                          .all()
-        if readings:
-            # we really only care about the latest reading
-            reading = sorted(readings, key=lambda r: r.taken)[-1]
+        """
+        Check readings for the given probe, within the time window defined by
+        the given cutoff.
+        """
+        # we really only care about the latest reading
+        reading = session.query(tempmon.Reading)\
+                         .filter(tempmon.Reading.probe == probe)\
+                         .filter(tempmon.Reading.taken >= cutoff)\
+                         .order_by(tempmon.Reading.taken.desc())\
+                         .first()
+        if reading:
 
+            # is reading below critical min, or above critical max?
             if (reading.degrees_f <= probe.critical_temp_min or
                   reading.degrees_f >= probe.critical_temp_max):
                 self.update_status(probe, self.enum.TEMPMON_PROBE_STATUS_CRITICAL_TEMP, reading)
 
+            # is reading below "good" min?
             elif reading.degrees_f < probe.good_temp_min:
                 self.update_status(probe, self.enum.TEMPMON_PROBE_STATUS_LOW_TEMP, reading)
 
+            # is reading above "good" max?
             elif reading.degrees_f > probe.good_temp_max:
                 self.update_status(probe, self.enum.TEMPMON_PROBE_STATUS_HIGH_TEMP, reading)
 
             else: # temp is good
                 self.update_status(probe, self.enum.TEMPMON_PROBE_STATUS_GOOD_TEMP, reading)
 
-        else: # no readings for probe
-            self.update_status(probe, self.enum.TEMPMON_PROBE_STATUS_ERROR)
+            return True
 
-        return readings
+        else: # no current readings for probe
+            self.update_status(probe, self.enum.TEMPMON_PROBE_STATUS_ERROR)
+            return False
 
     def update_status(self, probe, status, reading=None):
         data = {