diff --git a/ExtensionLoader/ExtensionLoader.cs b/ExtensionLoader/ExtensionLoader.cs
index ceb1b772..cd89567b 100644
--- a/ExtensionLoader/ExtensionLoader.cs
+++ b/ExtensionLoader/ExtensionLoader.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Reflection;
 using System.CodeDom.Compiler;
 using System.IO;
+using System.Text;
 
 namespace ExtensionLoader
 {
@@ -95,9 +96,17 @@ namespace ExtensionLoader
             {
                 CompilerResults results = CSCompiler.CompileAssemblyFromFile(CSCompilerParams, name);
                 if (results.Errors.Count == 0)
+                {
                     LoadAssemblyExtensions(results.CompiledAssembly, extensionList);
+                }
                 else
-                    throw new ExtensionException("Error(s) compiling " + name);
+                {
+                    StringBuilder errors = new StringBuilder();
+                    errors.AppendLine("Error(s) compiling " + name);
+                    foreach (CompilerError error in results.Errors)
+                        errors.AppendFormat(" Line {0}: {1}{2}", error.Line, error.ErrorText, Environment.NewLine);
+                    throw new ExtensionException(errors.ToString());
+                }
             }
 
             if (assignableInterfaces != null)
@@ -145,10 +154,7 @@ namespace ExtensionLoader
                         }
                     }
                 }
-                catch (Exception e)
-                {
-                    throw new ExtensionException("Unrecognized extension " + f, e);
-                }
+                catch (Exception) { }
             }
 
             return plugins;
diff --git a/Programs/Simian/DoubleDictionary.cs b/Programs/Simian/DoubleDictionary.cs
index dc696e6a..afc21636 100644
--- a/Programs/Simian/DoubleDictionary.cs
+++ b/Programs/Simian/DoubleDictionary.cs
@@ -25,8 +25,19 @@ namespace Simian
         {
             lock (syncObject)
             {
-                Dictionary1.Add(key1, value);
-                Dictionary2.Add(key2, value);
+                if (Dictionary1.ContainsKey(key1))
+                {
+                    if (!Dictionary2.ContainsKey(key2))
+                        throw new ArgumentException("key1 exists in the dictionary but not key2");
+                }
+                else if (Dictionary2.ContainsKey(key2))
+                {
+                    if (!Dictionary1.ContainsKey(key1))
+                        throw new ArgumentException("key2 exists in the dictionary but not key1");
+                }
+
+                Dictionary1[key1] = value;
+                Dictionary2[key2] = value;
             }
         }
 
@@ -81,5 +92,15 @@ namespace Simian
                     action(value);
             }
         }
+
+        public TValue this[TKey1 key1]
+        {
+            get { return Dictionary1[key1]; }
+        }
+
+        public TValue this[TKey2 key2]
+        {
+            get { return Dictionary2[key2]; }
+        }
     }
 }
diff --git a/Programs/Simian/Extensions/ImageDelivery.cs b/Programs/Simian/Extensions/ImageDelivery.cs
index 65dc7a81..d2910251 100644
--- a/Programs/Simian/Extensions/ImageDelivery.cs
+++ b/Programs/Simian/Extensions/ImageDelivery.cs
@@ -85,7 +85,6 @@ namespace Simian.Extensions
     {
         Simian server;
         Dictionary<UUID, ImageDownload> CurrentDownloads = new Dictionary<UUID, ImageDownload>();
-        BlockingQueue<ImageDownload> CurrentDownloadQueue = new BlockingQueue<ImageDownload>();
 
         public ImageDelivery()
         {