An error occurred while attaching module (Dynamicweb.Frontend.Content)

System.IO.IOException: The process cannot access the file 'D:\dynamicweb.net\Solutions\Gotcha\keflico.staging.dynamicweb-cms.com\Files\System\LiveIntegration\XmlTest.xml' because it is being used by another process.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
   at System.Xml.XmlDocument.Save(String filename)
   at NotificationSubscriberKeflico.XmlNotifier.OnNotify(String notification, NotificationArgs args)
   at Dynamicweb.Extensibility.Notifications.NotificationManager.Notify(String notification, NotificationArgs eventArgs)
   at Dynamicweb.Ecommerce.DynamicwebLiveIntegration.XmlGenerators.ProductInfoXmlGenerator.GenerateProductInfoXml(Settings currentSettings, Dictionary`2 products, ProductInfoXmlGeneratorSettings settings, Logger logger)
   at Dynamicweb.Ecommerce.DynamicwebLiveIntegration.Products.ProductManager.BuildProductRequest(Settings settings, Dictionary`2 products, LiveContext context, Logger logger)
   at Dynamicweb.Ecommerce.DynamicwebLiveIntegration.Products.ProductManager.FetchProductInfosInternal(Dictionary`2 productsForRequest, ResponseCacheLevel productCacheLevel, LiveContext context, Settings settings, Logger logger, Boolean updateCache)
   at Dynamicweb.Ecommerce.DynamicwebLiveIntegration.Products.ProductManager.FetchProductInfos(Dictionary`2 products, LiveContext context, Settings settings, Logger logger, Boolean doCurrencyCheck, Boolean updateCache)
   at Dynamicweb.Ecommerce.DynamicwebLiveIntegration.Products.ProductPriceProvider.PreparePrices(PriceContext context, IEnumerable`1 selections)
   at Dynamicweb.Ecommerce.Prices.PriceManager.PreparePrices(PriceContext context, IEnumerable`1 selections)
   at Dynamicweb.Ecommerce.Frontend.Frontend.ListProducts(ProductCollection products, String groupsIdent, Boolean hasBeenSorted)
   at Dynamicweb.Ecommerce.Frontend.Frontend.GetProductsFromIndexQuery(ProductCatalogShowType settingsType)
   at Dynamicweb.Ecommerce.Frontend.Frontend.EcomRender()
   at Dynamicweb.Ecommerce.Frontend.Frontend.GetContent()
   at Dynamicweb.Frontend.Content.GetModuleOutput(Paragraph paragraph, PageView pageview)