Launcher error messageboxes, more easily controllable & better looking swimming, oxygen tank bugfixes, loading screen coroutine bugfix

Subsurface/Source/Sounds/Sound.cs

@@ -234,11 +234,11 @@ namespace Subsurface
 
             loadedSounds.Remove(this);
 
-            System.Diagnostics.Debug.WriteLine("Removing sound " + filePath + " (buffer id" + AlBufferId + ")");
-
             if (alSourceId>0 && SoundManager.IsPlaying(alSourceId))
             {
+                ALHelper.Check();
                 SoundManager.Stop(alSourceId);
+                ALHelper.Check();
             }
 
             foreach (Sound s in loadedSounds)
@@ -246,6 +246,8 @@ namespace Subsurface
                 if (s.oggSound == oggSound) return;
             }
 
+            System.Diagnostics.Debug.WriteLine("Removing sound " + filePath + " (buffer id" + AlBufferId + ")");
+
             SoundManager.ClearAlSource(AlBufferId);
             oggSound.Dispose();
         }