Found the source of my AVG Free 8.0 Error 0x80070014

Found the problem (in my system, anyway)...turns out it is Ad-Aware. The previous versions offered Ad-Watch (realtime spyware protection) as a pay-for option. The latest version of Ad-Aware Free (Ad-AwareAE, a.k.a. "Anniversary Edition") includes Ad-Watch in the package. It was not sufficient to disable it; I had to REMOVE Ad-Aware to make sure there was no issue. Apparently there is still some functionality remaining even when disabled--it is possible that a reboot or two with it disabled may have been enough, but I went ahead and removed Ad-Aware completely, rebooted, installed AVG without an issue, then re-installed Ad-Aware, rebooted and all is well. So far, everything seems to work as planned.

Hope that helps...