I\'m having issues grasping how exactly to handle threads when using GeckoFX- it seems to throw errors constantly when trying to use the GeckoWebBrowser in other threads.
This will solve your prob, put it at the end of your nav request:
myGeckoFxBrowser.Navigate("about:blank"); myGeckoFxBrowser.Document.Cookie = ""; myGeckoFxBrowser.Stop();