Well 0x8007001F has not do to with some installers.Before I had another security suites installed,nothing wrong happend.I found that other users have the same problem without a clear solution(http://forum.avast.com/index.php?topic=76471.0,for instance)
Who says there is no clear solution? The clear solution in that topic was to run the specific removal utility of older security tools that were previously installed, then the removal utility for Avast (with reboots in between and from Windows Safe Mode in ALL uninstallations / removals) and to download the latest stable version of Avast anew.
Of course, after installation, reboot immediately again, test for several days and run the registration again.
BTW, under Windows Safe Mode, you can check Device Manager too so to find any old driver that may have some problem, and repeat the check under Normal Mode for comparison.
To be completely clear, the "Add/Remove Programs" normal method of uninstallation for security tools is usually NOT enough, and that's why there are specific removal utilities from each producer.