When I started avast, the splash screen came up, and said it was testing my memory. Soon enough, it found a virus, so I asked avast to remove it for me. After avast finished scanning, it said that I should restart my computer so it can perform a check and delete the found virus. When I pressed OK, it said "A required privilege is not held by this client, avast cannot reboot operating system," and the program just ended. It didn't restart or anything. Can someone help me, please?