To reproduce: add a RadMap with a Bing provider, select the canvas "Aerial with labels on demand" and zoom in all the way. It always gets the following exception:

System.ArgumentException: Parameter is not valid.
   at System.Drawing.Image.FromStream(Stream stream, Boolean useEmbeddedColorManagement, Boolean validateImageData)
   at Telerik.WinControls.UI.MapTileDownloader.TileDownloadDataCompleted(Object sender, DownloadDataCompletedEventArgs e)
   at System.Net.WebClient.OnDownloadDataCompleted(DownloadDataCompletedEventArgs e)

The issue is reproducible in Demo application with the Bing examples.

Workaround:

        public RadForm1()
        {
            InitializeComponent();

            string cacheFolder = @"..\..\cache";
            BingRestMapProvider bingProvider = new Telerik.WinControls.UI.BingRestMapProvider();
            bingProvider.TileDownloader = new CustomMapTileDownloader();
            bingProvider.UseSession = true;
            bingProvider.BingKey = "your bing key";
            LocalFileCacheProvider cache = new LocalFileCacheProvider(cacheFolder);
            bingProvider.CacheProvider = cache;
            this.radMap1.Providers.Add(bingProvider);
             
        }

        public class CustomMapTileDownloader : MapTileDownloader
        {
            protected override void TileDownloadDataCompleted(object sender, System.Net.DownloadDataCompletedEventArgs e)
            {
                TileInfo tileInfo = ((TileInfo)e.UserState);

                if (e.Error == null)
                {
                    try
                    {
                        using (MemoryStream ms = new MemoryStream(e.Result))
                        {
                            Image img = Image.FromStream(ms, true, true);
                            tileInfo.Content = e.Result;

                            this.OnTileDownloadComplete(new TileInfoEventArgs(tileInfo));

                            lock (this.webClientsPoolLockObject)
                            {
                                this.webClientsPool[tileInfo.Quadkey].DownloadDataCompleted -= this.TileDownloadDataCompleted;
                                this.webClientsPool.Remove(tileInfo.Quadkey);
                                this.webRequestCache.Remove(tileInfo.Quadkey);
                            }
                        }
                    }
                    catch (Exception)
                    {
                        
                        
                    }
                           
                    
                }
                else
                {
                    if (this.ShouldRetryDownload(e.Error))
                    {
                        Uri uri = this.webRequestCache[tileInfo.Quadkey];

                        lock (this.webClientsPoolLockObject)
                        {
                            uri = new Uri(this.webClientsPool[tileInfo.Quadkey].BaseAddress);
                            this.webClientsPool[tileInfo.Quadkey].DownloadDataCompleted -= this.TileDownloadDataCompleted;
                            this.webClientsPool.Remove(tileInfo.Quadkey);
                            this.webRequestCache.Remove(tileInfo.Quadkey);
                        }

                        this.BeginDownloadTile(uri, tileInfo);
                    }
                }
            }
        }
    }