Index: System.Data.SQLite/SQLiteConnectionPool.cs
==================================================================
--- System.Data.SQLite/SQLiteConnectionPool.cs
+++ System.Data.SQLite/SQLiteConnectionPool.cs
@@ -111,30 +111,30 @@
 
     /// <summary>
     /// Attempt to pull a pooled connection out of the queue for active duty
     /// </summary>
     /// <param name="fileName">The filename for a desired connection</param>
-    /// <param name="maxPoolSize">The maximum size the connection pool for the filename can be</param>
-    /// <param name="version">The pool version the returned connection will belong to</param>
-    /// <returns>Returns NULL if no connections were available.  Even if none are, the poolversion will still be a valid pool version</returns>
+    /// <param name="maxPoolSize">The maximum size the connection pool for the filename can be</param>
+    /// <param name="version">The pool version the returned connection will belong to</param>
+    /// <returns>Returns NULL if no connections were available.  Even if none are, the poolversion will still be a valid pool version</returns>
     internal static SQLiteConnectionHandle Remove(string fileName, int maxPoolSize, out int version)
     {
       lock (_connections)
       {
         Pool queue;
 
-        // Default to the highest pool version
+        // Default to the highest pool version
         version = _poolVersion;
 
         // If we didn't find a pool for this file, create one even though it will be empty.
         // We have to do this here because otherwise calling ClearPool() on the file will not work for active connections
         // that have never seen the pool yet.
         if (_connections.TryGetValue(fileName, out queue) == false)
         {
           queue = new Pool(_poolVersion, maxPoolSize);
-          _connections.Add(fileName, queue);
-
+          _connections.Add(fileName, queue);
+
           return null;
         }
 
         // We found a pool for this file, so use its version number
         version = queue.PoolVersion;
@@ -146,19 +146,21 @@
         Queue<WeakReference> poolQueue = queue.Queue;
         if (poolQueue == null) return null;
 
         while (poolQueue.Count > 0)
         {
-          WeakReference cnn = poolQueue.Dequeue();
+          WeakReference cnn = poolQueue.Dequeue();
+          if (cnn == null) continue;
           SQLiteConnectionHandle hdl = cnn.Target as SQLiteConnectionHandle;
           if ((hdl != null) && !hdl.IsClosed && !hdl.IsInvalid)
           {
-            Interlocked.Increment(ref _poolOpened);
+            Interlocked.Increment(ref _poolOpened);
             return hdl;
           }
+          cnn.Target = null;
           GC.KeepAlive(hdl);
-        }
+        }
         return null;
       }
     }
 
     /// <summary>
@@ -176,16 +178,18 @@
 
           Queue<WeakReference> poolQueue = pair.Value.Queue;
 
           while (poolQueue.Count > 0)
           {
-            WeakReference cnn = poolQueue.Dequeue();
+            WeakReference cnn = poolQueue.Dequeue();
+            if (cnn == null) continue;
             SQLiteConnectionHandle hdl = cnn.Target as SQLiteConnectionHandle;
             if (hdl != null)
             {
               hdl.Dispose();
             }
+            cnn.Target = null;
             GC.KeepAlive(hdl);
           }
           
           // Keep track of the highest revision so we can go one higher when we're finished
           if (_poolVersion <= pair.Value.PoolVersion)
@@ -216,16 +220,18 @@
           Queue<WeakReference> poolQueue = queue.Queue;
           if (poolQueue == null) return;
 
           while (poolQueue.Count > 0)
           {
-            WeakReference cnn = poolQueue.Dequeue();
+            WeakReference cnn = poolQueue.Dequeue();
+            if (cnn == null) continue;
             SQLiteConnectionHandle hdl = cnn.Target as SQLiteConnectionHandle;
             if (hdl != null)
             {
               hdl.Dispose();
             }
+            cnn.Target = null;
             GC.KeepAlive(hdl);
           }
         }
       }
     }
@@ -279,16 +285,18 @@
       Queue<WeakReference> poolQueue = queue.Queue;
       if (poolQueue == null) return;
 
       while (poolQueue.Count > target)
       {
-        WeakReference cnn = poolQueue.Dequeue();
+        WeakReference cnn = poolQueue.Dequeue();
+        if (cnn == null) continue;
         SQLiteConnectionHandle hdl = cnn.Target as SQLiteConnectionHandle;
         if (hdl != null)
         {
           hdl.Dispose();
         }
+        cnn.Target = null;
         GC.KeepAlive(hdl);
       }
     }
   }
 }