I rebooted several times but the scanner still remained blank.
I just uninstalled and then reinstalled avast 5 (i think as my internet was off it didn't download the VPS and it wouldn't even turn on, i did manage to fix that) However even after the reinstall the scanner still doesn't work..i read it could be to do with it replacing the avast 4.8, but thats now gone aswell, it's strange.