Hello Chan,
I am sorry to hear that. Please follow the steps from this article http://support.avg.com/SupportArticleView?urlname=How-to-resolve-an-issue-when-AVG-shows-the-UI-Failed-to-load-error and check if that fix the issue.
If you face any difficulties, please send me the screenshot http://avgclick.me/getscreenshot of the error message to assist further.