Did anything improve after running the troubleshooter?
Could you please run it once more and click the "View detailed information" on the results page, then take a screenshot of that for me.
If your updates are not fixed, let try a reinstall of your antivirus.
Before you uninstall, please download the installer in order to reinstall your AV when you are done without browsing the internet. If you would like to keep AVG, you can get it here.
Unless you have the paid version, I would actually recommend switching to AVAST
or Microsoft Security Essentials.
First, uninstall AVG using the "Programs and Features" menu in the Control Panel. Then download and run the AVG Remover
to make sure everything is gone.Please don't surf the internet while you don't have an antivirus installed.
While your antivirus is temporarily gone, could you please try updating windows. This will check if maybe there is a conflict with your AV.
You can now reinstall the AV of your choice.
Please let me know if you can now update, and if not, is the error code still the same?