malicous url blocked

for some reson i keep getting a pop up saying malicous url blocked with a picture of the twitter logo on and my partner also got in at the the same time on a different pc but none of us go on twitter it want let us log on to hotmail or facebook at all cn you please help

First ensure that you have the latest virus definitions, 110420-1.

The twitter logo in the avast alert is correct, but can be removed, avastUI, Settings, Community and uncheck the two options in the Community features, see image. The first gets rid of the Like button the second gets rid of the twitter icon in the alert.