diff --git a/MediaBrowser.Controller/Entities/BaseItem.cs b/MediaBrowser.Controller/Entities/BaseItem.cs
index 83690c243..c59094cbf 100644
--- a/MediaBrowser.Controller/Entities/BaseItem.cs
+++ b/MediaBrowser.Controller/Entities/BaseItem.cs
@@ -1,4 +1,5 @@
-using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Common.Extensions;
+using MediaBrowser.Controller.Configuration;
 using MediaBrowser.Controller.IO;
 using MediaBrowser.Controller.Library;
 using MediaBrowser.Controller.Localization;
@@ -193,18 +194,23 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// The _file system stamp
         /// </summary>
-        private string _fileSystemStamp;
+        private Guid? _fileSystemStamp;
         /// <summary>
         /// Gets a directory stamp, in the form of a string, that can be used for
         /// comparison purposes to determine if the file system entries for this item have changed.
         /// </summary>
         /// <value>The file system stamp.</value>
         [IgnoreDataMember]
-        public string FileSystemStamp
+        public Guid FileSystemStamp
         {
             get
             {
-                return _fileSystemStamp ?? (_fileSystemStamp = GetFileSystemStamp());
+                if (!_fileSystemStamp.HasValue)
+                {
+                    _fileSystemStamp = GetFileSystemStamp();
+                }
+
+                return _fileSystemStamp.Value;
             }
         }
 
@@ -226,12 +232,12 @@ namespace MediaBrowser.Controller.Entities
         /// comparison purposes to determine if the file system entries for this item have changed.
         /// </summary>
         /// <returns>Guid.</returns>
-        private string GetFileSystemStamp()
+        private Guid GetFileSystemStamp()
         {
             // If there's no path or the item is a file, there's nothing to do
             if (LocationType != LocationType.FileSystem || !ResolveArgs.IsDirectory)
             {
-                return string.Empty;
+                return Guid.Empty;
             }
 
             var sb = new StringBuilder();
@@ -247,7 +253,7 @@ namespace MediaBrowser.Controller.Entities
                 sb.Append(file.cFileName);
             }
 
-            return sb.ToString();
+            return sb.ToString().GetMD5();
         }
 
         /// <summary>
diff --git a/MediaBrowser.Controller/Providers/BaseMetadataProvider.cs b/MediaBrowser.Controller/Providers/BaseMetadataProvider.cs
index dd03c88de..ed9e50f82 100644
--- a/MediaBrowser.Controller/Providers/BaseMetadataProvider.cs
+++ b/MediaBrowser.Controller/Providers/BaseMetadataProvider.cs
@@ -142,7 +142,7 @@ namespace MediaBrowser.Controller.Providers
             // Save the file system stamp for future comparisons
             if (RefreshOnFileSystemStampChange)
             {
-                data.FileSystemStamp = GetCurrentFileSystemStamp(item);
+                data.FileStamp = GetCurrentFileSystemStamp(item);
             }
 
             item.ProviderData[Id] = data;
@@ -229,7 +229,7 @@ namespace MediaBrowser.Controller.Providers
         /// <returns><c>true</c> if [has file system stamp changed] [the specified item]; otherwise, <c>false</c>.</returns>
         protected bool HasFileSystemStampChanged(BaseItem item, BaseProviderInfo providerInfo)
         {
-            return !String.Equals(GetCurrentFileSystemStamp(item), providerInfo.FileSystemStamp);
+            return GetCurrentFileSystemStamp(item) != providerInfo.FileStamp;
         }
 
         /// <summary>
@@ -287,7 +287,7 @@ namespace MediaBrowser.Controller.Providers
         /// </summary>
         /// <param name="item">The item.</param>
         /// <returns>Guid.</returns>
-        private string GetCurrentFileSystemStamp(BaseItem item)
+        private Guid GetCurrentFileSystemStamp(BaseItem item)
         {
             if (UseParentFileSystemStamp(item) && item.Parent != null)
             {
diff --git a/MediaBrowser.Controller/Providers/BaseProviderInfo.cs b/MediaBrowser.Controller/Providers/BaseProviderInfo.cs
index 23779d382..6262392fd 100644
--- a/MediaBrowser.Controller/Providers/BaseProviderInfo.cs
+++ b/MediaBrowser.Controller/Providers/BaseProviderInfo.cs
@@ -16,7 +16,7 @@ namespace MediaBrowser.Controller.Providers
         /// Gets or sets the file system stamp.
         /// </summary>
         /// <value>The file system stamp.</value>
-        public string FileSystemStamp { get; set; }
+        public Guid FileStamp { get; set; }
         /// <summary>
         /// Gets or sets the last refresh status.
         /// </summary>
diff --git a/MediaBrowser.Controller/Providers/Music/LastfmArtistProvider.cs b/MediaBrowser.Controller/Providers/Music/LastfmArtistProvider.cs
index 165b996f6..c846fcd97 100644
--- a/MediaBrowser.Controller/Providers/Music/LastfmArtistProvider.cs
+++ b/MediaBrowser.Controller/Providers/Music/LastfmArtistProvider.cs
@@ -76,7 +76,11 @@ namespace MediaBrowser.Controller.Providers.Music
                     var ms = new MemoryStream();
                     JsonSerializer.SerializeToStream(result.artist, ms);
 
-                    cancellationToken.ThrowIfCancellationRequested();
+                    if (cancellationToken.IsCancellationRequested)
+                    {
+                        ms.Dispose();
+                        cancellationToken.ThrowIfCancellationRequested();
+                    }
 
                     await _providerManager.SaveToLibraryFilesystem(item, Path.Combine(item.MetaLocation, LocalMetaFileName), ms, cancellationToken).ConfigureAwait(false);
                     
diff --git a/MediaBrowser.Server.Implementations/Providers/ProviderManager.cs b/MediaBrowser.Server.Implementations/Providers/ProviderManager.cs
index 36e6416ce..979679916 100644
--- a/MediaBrowser.Server.Implementations/Providers/ProviderManager.cs
+++ b/MediaBrowser.Server.Implementations/Providers/ProviderManager.cs
@@ -125,14 +125,14 @@ namespace MediaBrowser.Server.Implementations.Providers
 
             BaseProviderInfo supportedProvidersInfo;
 
-            var supportedProvidersValue = string.Join("+", supportedProviders.Select(i => i.GetType().Name));
+            var supportedProvidersValue = string.Join(string.Empty, supportedProviders.Select(i => i.GetType().Name));
             var providersChanged = false;
 
             item.ProviderData.TryGetValue(_supportedProvidersKey, out supportedProvidersInfo);
             if (supportedProvidersInfo != null)
             {
                 // Force refresh if the supported providers have changed
-                providersChanged = force = force || !string.Equals(supportedProvidersInfo.FileSystemStamp, supportedProvidersValue);
+                providersChanged = force = force || !string.Equals(supportedProvidersInfo.CustomData, supportedProvidersValue);
 
                 // If providers have changed, clear provider info and update the supported providers hash
                 if (providersChanged)
@@ -144,7 +144,7 @@ namespace MediaBrowser.Server.Implementations.Providers
 
             if (providersChanged)
             {
-                supportedProvidersInfo.FileSystemStamp = supportedProvidersValue;
+                supportedProvidersInfo.CustomData = supportedProvidersValue;
             }
 
             if (force) item.ClearMetaValues();