OK lets see if there is a conflict somewhere
This is a clean boot where we will initially just run MS services and Avast
In the search box type Msconfig and select the programme that appears at the top
1.In the System Configuration Utility dialog box, click Selective Startup on the General tab.
2.Click to clear the Load Startup Items check box.
NoteThe Use Original Boot.ini check box is unavailable.
3.Click the Services tab.
4.Click to select the
Hide All Microsoft Services check box.
5.Click Disable All, and then tick any Avast related services
6.Click OK.
7.When you are prompted, click Restart.
8.Now try an Avast quick scan