On your computer should be a file called C:\Users\Luke\Documents\MBR.dat could you locate this with the virus chest and upload to Avast please

Open the Avast GUI
Select Maintenance
Select Virus chest
Right click anywhere in the white space
Click add
Navigate to C:\Users\Luke\Documents\MBR.dat
Select that file and add to the chest
From the chest right click the file and select send to virus labs
Fill in the short form and next time you update it will go to Avast for further analysis