The conflict between update 3292 for both free and paid-for versions of the software causes systems to go into an infinite crash loop, the company said.
AVG has withdrawn the update and published an advisory on how to get affected systems running again and links to FAQs.
AVG also said it will release a program to ensure that the fix is completed automatically as soon as possible.
Users who are running Windows 7 and have not downloaded and installed update 3292 will be unaffected, the company said.
This story was first published by Computer Weekly