-

diff --git a/main/external/nrefactory b/main/external/nrefactory
--- a/main/external/nrefactory
+++ b/main/external/nrefactory
@@ -1 +1 @@
-Subproject commit 927cc8fd55b38af111eff07c018f2d4bbac74bc0
+Subproject commit 927cc8fd55b38af111eff07c018f2d4bbac74bc0-dirty
diff --git a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.TypeSystem/TypeSystemService.cs b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.TypeSystem/TypeSystemService.cs
index e134429..381c668 100644
--- a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.TypeSystem/TypeSystemService.cs
+++ b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.TypeSystem/TypeSystemService.cs
@@ -506,27 +506,17 @@ namespace MonoDevelop.Ide.TypeSystem
 
 		static string InternalGetCacheDirectory (FilePath filename)
 		{
-			CanonicalizePath (ref filename);
 			string result;
-			var nameNoExtension = Path.GetFileName (filename);
-			var derivedDataPath = UserProfile.Current.CacheDir.Combine ("DerivedData");
+
+			CanonicalizePath (ref filename);
+			var assemblyCacheRoot = GetAssemblyCacheRoot (filename);
+
 			try {
-				// First try to access what we think could be the correct file directly
-				if (CheckCacheDirectoryIsCorrect (filename, derivedDataPath.Combine (nameNoExtension), out result))
-					return result;
-				
-				if (Directory.Exists (derivedDataPath)) {
-					// next check any directory which contains the filename
-					foreach (var subDir in Directory.EnumerateDirectories (derivedDataPath).Where (s=> s.Contains (nameNoExtension))) {
-						if (CheckCacheDirectoryIsCorrect (filename, subDir, out result)) {
-							return result;
-						}
-					}
-/*					// Finally check every remaining directory
-					foreach (var subDir in subDirs.Where (s=> !s.Contains (nameNoExtension)))
-						if (CheckCacheDirectoryIsCorrect (filename, subDir, out result))
-							return result;*/
-				}
+				if (!Directory.Exists (assemblyCacheRoot))
+					return null;
+				foreach (var dir in Directory.EnumerateDirectories (assemblyCacheRoot))
+					if (CheckCacheDirectoryIsCorrect (filename, dir, out result))
+						return result;
 			} catch (Exception e) {
 				LoggingService.LogError ("Error while getting derived data directories.", e);
 			}
@@ -634,26 +624,29 @@ namespace MonoDevelop.Ide.TypeSystem
 			}
 		}
 
-		static string GetName (string baseName, int i)
+		static string GetAssemblyCacheRoot (string filename)
 		{
-			if (i == 0)
-				return baseName;
-			return baseName + "-" + i;
+			string derivedDataPath = UserProfile.Current.CacheDir.Combine ("DerivedData");
+			string name = Path.GetFileName (filename);
+			return Path.Combine (derivedDataPath, name + "-" + name.GetHashCode ().ToString ("x")); 	
+		}
+
+		static IEnumerable<string> GetPossibleCacheDirNames (string baseName)
+		{
+			int i = 0;
+			while (i < 4096) {
+				yield return Path.Combine (baseName, i.ToString ());
+				i++;
+			}
+			throw new Exception ("Too many cache directories");
 		}
 
 		static string CreateCacheDirectory (FilePath fileName)
 		{
 			CanonicalizePath (ref fileName);
 			try {
-				string derivedDataPath = UserProfile.Current.CacheDir.Combine ("DerivedData");
-				string name = Path.GetFileName (fileName);
-				string baseName = Path.Combine (derivedDataPath, name);
-				int i = 0;
-				while (Directory.Exists (GetName (baseName, i)))
-					i++;
-				
-				string cacheDir = GetName (baseName, i);
-				
+				string cacheRoot = GetAssemblyCacheRoot (fileName);
+				string cacheDir = GetPossibleCacheDirNames (cacheRoot).First (d => !Directory.Exists (d));
 				Directory.CreateDirectory (cacheDir);
 
 				File.WriteAllText (