No, it probably wasn't something that you actually did, but more likely an issue with a problematic software install or un-install.
But if you wouldn't mind a suggestion from someone who actually used to work for an AVG reseller, consider removing it permanently and give Link Removed due to 404 Error a go. Download, install, update and run a complete scan. Also make sure you double check the shell value of the registry key, I noted above otherwise the problem may re-appear after a reboot.
Good luck
Randy