Thank you 124, I removed AVG with the tool and reinstalled it (I have a 64 bit system), however the problem still occurred.
I have now, after many years being an avid AVG fan and follower, have ditched it for Kapersky (30 day trial) antivirus. It did find two trojans, and seems to be running OK as is my internet explorer.
Think it got to the point where "free" is not always the best.
Many thanks for your assistance.