+ Don't allow processing of the Timer changed queue while the world is loading or saving.

* Removes the risk of inconsistency [warnings] generated by timers that tick with handlers that modify World.Items and World.Mobiles during I/O.

+ Update description of Core.TickCount.

RunUO.exe.config

@@ -1,10 +1,12 @@
-<?xml version="1.0"?>
-<configuration>
-  <runtime>
-    <gcServer enabled="true" />
-  </runtime>
-<!--
-  MONO/Linux users will need to uncomment and modify the following line:
--->
-<!--<dllmap dll="libz" target="/lib/x86_64-linux-gnu/libz.so.1" />-->
+<?xml version="1.0"?>
+
+<configuration>
+	<startup>
+		<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0" />
+	</startup>
+	<runtime>
+		<gcServer enabled="true" />
+	</runtime>
+	<!--MONO/Linux users will need to uncomment and modify the following line:-->
+	<!--<dllmap dll="libz" target="/lib/x86_64-linux-gnu/libz.so.1" />-->
 </configuration>

Server/Main.cs

@@ -107,23 +107,17 @@ namespace Server
 		public static Thread Thread { get { return m_Thread; } }
 		public static MultiTextWriter MultiConsoleOut { get { return m_MultiConOut; } }
 
-		/* DateTime.Now and DateTime.UtcNow are based on actual system clock time.
+		/* 
+		 * DateTime.Now and DateTime.UtcNow are based on actual system clock time.
 		 * The resolution is acceptable but large clock jumps are possible and cause issues.
 		 * GetTickCount and GetTickCount64 have poor resolution.
 		 * GetTickCount64 is unavailable on Windows XP and Windows Server 2003.
 		 * Stopwatch.GetTimestamp() (QueryPerformanceCounter) is high resolution, but
-		 * somewhat expensive to call and unreliable with certain system configurations.
+		 * somewhat expensive to call because of its defference to DateTime.Now,
+		 * which is why Stopwatch has been used to verify HRT before calling GetTimestamp(),
+		 * enabling the usage of DateTime.UtcNow instead.
 		 */
 
-		/* The following implementation contains an effective substitute for GetTickCount64 that
-		 * is reliable as long as it is retrieved once every 2^32 ms (~49 days).
-		 */
-
-		/* We don't really need this, but it may be useful in the future.
-		private static ThreadLocal<long> _HighOrder = new ThreadLocal<long>();
-		private static ThreadLocal<uint> _LastTickCount = new ThreadLocal<uint>();
-		*/
-
 		private static readonly bool _HighRes = Stopwatch.IsHighResolution;
 
 		private static readonly double _HighFrequency = 1000.0 / Stopwatch.Frequency;

Server/Timer.cs

@@ -313,6 +313,12 @@ namespace Server
 
 				while ( !Core.Closing )
 				{
+					if (World.Loading || World.Saving)
+					{
+						m_Signal.WaitOne(1, false);
+						continue;
+					}
+
 					ProcessChanged();
 
 					loaded = false;