I'm having a similar problem, except I think I know why it's happening, just not how to fix it. In order to install the new version, I need to quit avast; but, since it seems to be set to run perpetually, I can't install the new product. I click "terminate", and the application terminates, but then opens again instantly. I just need to know how to disable this perpetual running function so I can install the new version--essentially just replace the existing version with the version I just downloaded, which is impossible while the existing version is still running.