Index: Tuner.cs
===================================================================
--- Tuner.cs	(revision 26328)
+++ Tuner.cs	(working copy)
@@ -428,8 +428,10 @@
       {
         AMTunerSignalStrength signalStrength;
         _tuner.SignalPresent(out signalStrength);
-        _tunerLocked = (signalStrength == AMTunerSignalStrength.SignalPresent ||
-                        signalStrength == AMTunerSignalStrength.HasNoSignalStrength);
+        // Some tuners report values outside the range specified by the DirectShow
+        // interface when they are locked. This means it is best to assume the
+        // tuner is locked unless the tuner reports no signal.
+        _tunerLocked = (signalStrength != AMTunerSignalStrength.NoSignal);
       }
       catch (TvExceptionSWEncoderMissing)
       {