I have a TWebGMap on a TFrame, and I've noticed that this sometimes causes problems when calling Launch where some javascript errors appear. I found a solution for me is to change the Launch method to call InitNew before calling Load:
(FWebBrowser.Document as IPersistStreamInit).InitNew;
(FWebBrowser.Document as IPersistStreamInit).Load(TStreamAdapter.Create(aStream));
(FWebBrowser.Document as IPersistStreamInit).Load(TStreamAdapter.Create(aStream));
--Troy