Fix adding new feeds and version check at start-up

Application/MainWindow.xaml.cs

@@ -107,6 +107,10 @@ namespace FeedCenter
             InitializeFeed();
 
             // Check for update
+            if (Settings.Default.CheckVersionAtStartup)
+                UpdateCheck.CheckForUpdate();
+
+            // Show the link if updates are available
             if (UpdateCheck.UpdateAvailable)
                 newVersionLink.Visibility = Visibility.Visible;
 
@@ -782,7 +786,7 @@ namespace FeedCenter
             // Create and configure the new feed
             var feed = Feed.Create(_database);
             feed.Source = feedUrl;
-            feed.Category = _database.Categories.First(category => category.IsDefault);
+            feed.Category = _database.DefaultCategory;
 
             // Read the feed for the first time
             var feedReadResult = feed.Read(_database);