fixes #255 - Access to the path is denied.

MediaBrowser.Server.Implementations/Providers/ProviderManager.cs

@@ -374,6 +374,14 @@ namespace MediaBrowser.Server.Implementations.Providers
 
                 try
                 {
+                    // If the file already exists but is hidden, the below save will throw an UnauthorizedAccessException
+                    var existingFileInfo = new FileInfo(localPath);
+
+                    if (existingFileInfo.Exists && existingFileInfo.Attributes.HasFlag(FileAttributes.Hidden))
+                    {
+                        existingFileInfo.Delete();
+                    }
+
                     using (var fs = new FileStream(localPath, FileMode.Create, FileAccess.Write, FileShare.Read, StreamDefaults.DefaultFileStreamBufferSize, FileOptions.Asynchronous))
                     {
                         await img.CopyToAsync(fs, StreamDefaults.DefaultCopyToBufferSize, cancellationToken).ConfigureAwait(false);