diff --git a/OpenSim/Region/ScriptEngine/Interfaces/IScriptInstance.cs b/OpenSim/Region/ScriptEngine/Interfaces/IScriptInstance.cs
index f68612c15e..35ae44c315 100644
--- a/OpenSim/Region/ScriptEngine/Interfaces/IScriptInstance.cs
+++ b/OpenSim/Region/ScriptEngine/Interfaces/IScriptInstance.cs
@@ -52,7 +52,12 @@ namespace OpenSim.Region.ScriptEngine.Interfaces
     {
         bool Cancel();
         void Abort();
-        bool Wait(TimeSpan t);
+
+        /// <summary>
+        /// Wait for the work item to complete.
+        /// </summary>
+        /// <param name='t'>The number of milliseconds to wait.  Must be >= -1 (Timeout.Infinite).</param>
+        bool Wait(int t);
     }
 
     /// <summary>
diff --git a/OpenSim/Region/ScriptEngine/Shared/Instance/ScriptInstance.cs b/OpenSim/Region/ScriptEngine/Shared/Instance/ScriptInstance.cs
index 669cc3761c..bf19a42868 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Instance/ScriptInstance.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Instance/ScriptInstance.cs
@@ -595,7 +595,7 @@ namespace OpenSim.Region.ScriptEngine.Shared.Instance
                 if (!m_coopTermination)
                 {
                     // If we're not co-operative terminating then try and wait for the event to complete before stopping
-                    if (workItem.Wait(new TimeSpan((long)timeout * 100000)))
+                    if (workItem.Wait(timeout))
                         return true;
                 }
                 else
@@ -610,7 +610,7 @@ namespace OpenSim.Region.ScriptEngine.Shared.Instance
 
                     // For now, we will wait forever since the event should always cleanly terminate once LSL loop
                     // checking is implemented.  May want to allow a shorter timeout option later.
-                    if (workItem.Wait(TimeSpan.MaxValue))
+                    if (workItem.Wait(Timeout.Infinite))
                     {
                         if (DebugLevel >= 1)
                             m_log.DebugFormat(
diff --git a/OpenSim/Region/ScriptEngine/XEngine/XWorkItem.cs b/OpenSim/Region/ScriptEngine/XEngine/XWorkItem.cs
index 2ac5c315af..8dd7677d7f 100644
--- a/OpenSim/Region/ScriptEngine/XEngine/XWorkItem.cs
+++ b/OpenSim/Region/ScriptEngine/XEngine/XWorkItem.cs
@@ -57,8 +57,12 @@ namespace OpenSim.Region.ScriptEngine.XEngine
             wr.Abort();
         }
 
-        public bool Wait(TimeSpan t)
+        public bool Wait(int t)
         {
+            // We use the integer version of WaitAll because the current version of SmartThreadPool has a bug with the
+            // TimeSpan version.  The number of milliseconds in TimeSpan is an int64 so when STP casts it down to an 
+            // int (32-bit) we can end up with bad values.  This occurs on Windows though curious not on Mono 2.10.8
+            // (or very likely other versions of Mono at least up until 3.0.3).
             return SmartThreadPool.WaitAll(new IWorkItemResult[] {wr}, t, false);
         }
     }