My advice  is to  download the latest Free AVG installer to your desktop .

It is here: Latest Free AVG

If you have been having any trouble with AVG working properly. You may want to Uninstall AVG from control panel ->add/remove programs.  It may be wise to do this uninstall of AVG whether you've had problems or not.

If you do the old avg uninstall then you should Reboot before installing again.

If you are getting the nag prompts to update and  you follow their leads from the prompt you are getting, sometimes it is easy to end up asking for the paid version by mistake.  If they ask you for a credit card #, then you
took a wrong turn in their maze.  Try again. Or use the link above.