Tech.
as you can see in my original post, which you commented on,I have already carried out a re-installation before I asked for advice. I know this is the Avast forum ,but as I was made aware of Ewido through fellow posters on Avast and installed same on their recommendation.It proved to be good advice and I have been happy with results until this turned up That is why I did not think it would be inappropiate to ask for help.
DavidR
I think you are probably correct when you suggest that re-installing invalidates the 30 day trial , sounds sensible to me.I used to use the "free scan" option on their home page prior to downloading the 30 day trial version . What I liked abut it was the fact that it located "Hi-jacker.agent.a " and removed same.plus the Shield protection and auto updates. Once again , thank you for wise advice and assistance.