I would start by going back to AVG and find out why it is not removing it and then follow the links to their site where you will find the instructions on how to remove it or quarantine it. You could use system restore, but go back several weeks instead of days ( only system settings will change, not your personal stuff or programs ). You can use the Windows DVD repair instead of re-install ( or restore partition if it is a newer W8 computer ) to restore all the system files back to original, like new condition. Most of the more significant repair options will require you to go to Windows Updates and re-install all the updates.