Please check following sticky on AVG main forums:
Spent the last 4 hours trying to solve my problem without success !
I tried everything that you suggested but did not work.
Here are the course of events:
1. About a month ago got infected with a virus, and fixed it with AVG. After that for whatever reasons my AVG stopped working. I then tried to uninstall/reinstall it without success.
2. In the meanwhile I installed AVAST. My free trial ended today so I use their uninstall tools to erase any traces of AVAST in my computer's system.
3. Tried to install AVG this morning but got always the same error code "0XC0070643" message. I tried all I could with all the tools suggested, and it still not working. I really don't know now how to fix the whole thing. I like AVG, and I really want to reinstall it on my laptop.
Can you help ?
PS: I have in a compressed folder all my mfa/msi logs in case you need it.
Thank you !