I uninstalled avast! and ran the uninstall utility in Safe Mode, rebooting at each step along the way. I have completed the re-installation, rebooted, and chose "yes" to schedule a boot time scan; but, I had to move from the location when the scan had only progressed 5% and possibly made a mistake stopping it.
Stopping the scan shouldn't be a problem, it is only looking for infection and your problems don't seem to be related to any infection.
The installation doesn't need to do a boot-time scan to complete successfully, it has effectively done that before you reboot and if windows started after aborting the boot-time scan, then no problem you should OK.
Re the two NIS entries reported earlier:
There are two items which appear in MSCONFIG as disabled (ccApp and isCfgWiz) which I googled and both seem to be related to Norton.
Then it is back to monitoring avast and your browsing and see what the result is.
If they are disabled in msconfig, you cang go back in there and right click on them and you should be able to select delete.
I suppose a regular scan will do the same for me this evening but stopping it may have allowed a bug to stay around. I suppose I could repeat the installation process this evening if it becomes necessary. Again, keeping my fingers crossed. Thanks for your help.
I wouldn't make that supposition a boot-time scan can take a while and it differs from the regular on-demand scan as you can change the sensitivity and effectively what is scanned.
There should be no need to reinstall unless you are experiencing problems and you should report the problem first.