RelayDatabase: Added some default logging when clearing the cache, and removed the now-extraneous CheckedVesselsTable.
RelayDatabase: Added some default logging when clearing the cache, and removed the now-extraneous CheckedVesselsTable.

--- a/ModuleLimitedDataTransmitter.cs
+++ b/ModuleLimitedDataTransmitter.cs
@@ -145,13 +145,13 @@
 				{
 					return base.vessel;
 				}
-				else if (this.part != null)
+				else if (this.part != null && this.part.vessel != null)
 				{
 					return this.part.vessel;
 				}
-
 				else
 				{
+					this.LogError("Vessel and/or part reference are null, returning null vessel.");
 					return null;
 				}
 			}

--- a/ProtoAntennaRelay.cs
+++ b/ProtoAntennaRelay.cs
@@ -48,17 +48,24 @@
 		{
 			get
 			{
-				if (this.protoPart != null && this.protoPart.pVesselRef != null)
+				if (
+					this.protoPart != null &&
+					this.protoPart.pVesselRef != null &&
+					this.protoPart.pVesselRef.vesselRef != null
+				)
 				{
 					return this.protoPart.pVesselRef.vesselRef;
 				}
 				else
 				{
-					Tools.PostLogMessage("{0}: Could not fetch vessel!  {1}{2}{3}",
+					Tools.PostErrorMessage("{0}: Could not fetch vessel!  {1}{2}{3}",
 						this.ToString(),
-						this.protoPart == null ? "\n\tprotoPart=Null" : string.Empty,
-						this.protoPart != null && this.protoPart.pVesselRef == null ? "\n\tthis.protoPart.pVesselRef=Null" : string.Empty,
-						this.protoPart != null && this.protoPart.pVesselRef != null && this.protoPart.pVesselRef.vesselRef == null ? "\n\tthis.protoPart.pVesselRef.vesselRef=Null" : string.Empty
+						this.protoPart == null ? "\n\tprotoPart=null" : string.Empty,
+						this.protoPart != null && this.protoPart.pVesselRef == null ?
+							"\n\tthis.protoPart.pVesselRef=null" : string.Empty,
+						this.protoPart != null && this.protoPart.pVesselRef != null &&
+							this.protoPart.pVesselRef.vesselRef == null ?
+							"\n\tthis.protoPart.pVesselRef.vesselRef=null" : string.Empty
 					);
 					return null;
 				}

--- a/RelayDatabase.cs
+++ b/RelayDatabase.cs
@@ -72,9 +72,6 @@
 		// Vessel.id-keyed hash table of part counts, used for caching
 		private Dictionary<Guid, int> vesselPartCountTable;
 
-		// Vessel.id-keyed hash table of booleans to track what vessels have been checked so far this time.
-		public Dictionary<Guid, bool> CheckedVesselsTable;
-
 		private int cacheHits;
 		private int cacheMisses;
 
@@ -117,9 +114,16 @@
 		// Remove a vessel from the cache, if it exists.
 		public void DirtyVessel(Vessel vessel)
 		{
+			#if DEBUG
+			Tools.PostDebugMessage("RelayDatabase: Dirtying cache for vessel {0} in frame {1}",
+				vessel, new System.Diagnostics.StackTrace().ToString());
+			#else
+			Tools.PostLogMessage("RelayDatabase: Dirtying cache for vessel {0}", vessel.vesselName);
+			#endif
+
 			this.relayDatabase.Remove(vessel.id);
 			this.vesselPartCountTable.Remove(vessel.id);
-			this.relayDatabase.Remove(vessel.id);
+			this.bestRelayTable.Remove(vessel.id);
 		}
 
 		// Returns true if both the relayDatabase and the vesselPartCountDB contain the vessel id.
@@ -228,11 +232,33 @@
 		// Runs when the player requests a scene change, such as when changing vessels or leaving flight.
 		private void onSceneChange(GameScenes scene)
 		{
-			// If the active vessel is a real thing...
-			if (FlightGlobals.ActiveVessel != null)
-			{
-				// ... dirty its cache
-				this.onVesselEvent(FlightGlobals.ActiveVessel);
+			Tools.PostDebugMessage(
+				"RelayDatabase: caught onSceneChangeRequested in scene {0} to scene {1}.  ActiveVessel is {2}",
+				HighLogic.LoadedScene,
+				scene,
+				FlightGlobals.ActiveVessel == null ? "null" : FlightGlobals.ActiveVessel.vesselName
+			);
+
+			if (scene == GameScenes.FLIGHT)
+			{
+				if (scene == HighLogic.LoadedScene)
+				{
+					if (FlightGlobals.ActiveVessel != null)
+					{
+						Tools.PostDebugMessage("RelayDatabase: onSceneChange clearing {0} from cache.",
+							FlightGlobals.ActiveVessel.vesselName);
+
+						this.onVesselEvent(FlightGlobals.ActiveVessel);
+					}
+				}
+				else
+				{
+					Tools.PostLogMessage("RelayDatabase: onSceneChange clearing entire cache.");
+
+					this.relayDatabase.Clear();
+					this.bestRelayTable.Clear();
+					this.vesselPartCountTable.Clear();
+				}
 			}
 		}
 
@@ -394,7 +420,6 @@
 			this.relayDatabase = new Dictionary<Guid, List<IAntennaRelay>>();
 			this.bestRelayTable = new Dictionary<Guid, IAntennaRelay>();
 			this.vesselPartCountTable = new Dictionary<Guid, int>();
-			this.CheckedVesselsTable = new Dictionary<Guid, bool>();
 
 			this.cacheHits = 0;
 			this.cacheMisses = 0;