Hi cor-el, Solution worked ONCE - the next time I tried to access google calendar - problem returned

Hi cor-el, Solution worked ONCE - the next time I tried to access google calendar - problem returned. I cleared the DNS cache again and the calendar loaded ?? More advise needed please. I am not using any proxy or VPN that I know about, I use AVAST Premium protection, and run Ghostery as a Firefox extension - turning Ghostery on and off has no effect. I have tried the usual tricks - clear History Everything, uninstall and reinstall Firefox, etc.. Thanks, DougH