Hi Artras!
Update of my trials and tribulations:
Yes, very interesting, but convoluted experience here. I had downloaded the "setupeng.exe" at least three times and got the same results, i.e., the message indicating not all components there and to download either an Update or full program from the Internet. I compared the sizes of the downloads along with computing a checksum. Now, I didn't have an offical checksum to compare to, but the end results of the cheksum activity on the downloads wete the same ... so ... at least the downloaded data was consistent ... not necessarily correct ... just consistent.
Anway, while fuming, I rried using the expired software (trial Pro version) to scan the downloaded files and the scans seemed to work! Not 100%, but I have to assume the software at least gave me some capability even if the icons didn't show in the systray. Because of that, I attempted to run the trial Pro version and it fired up, started to perform the memory tests, i.e., the iniitial stuff it normally does, then it asked for a Pro version registration key as the Demo key had expired. Since I didn't have a key for the Pro version, I simply replied I had no key and the trial Pro version terminated. Well, as inquiring minds often do, I fired up the Pro trial version again and when it asked for the registration key, I inserted the registration key I had received for the free Home Edition version and waited to see what would happen. Well, low and behold ... it took it, contacted the Avast! web site and apparently made the necessary adjustments so that I now have the Home Edition installed, icons in the systray (after rebooting) and up and running.
While I am cautious at this juncture ... life is good again
Only the passage of time will I feel secure though, but at least it looks like I'm headed in the right direction.