🚀 go-pugleaf

Ted Neubauer --Thanks for your suggestion. Unfortunately it did not help me. The Registry keys mentioned were already deleted by the uninstallation of Adobe Reader 8.1.2. (I checked before and after.)
And another attempt today to install Reader 9 again went to 99.90% and stopped there as before. (In my case when the 99.90% level was reached, my Epson Scanner's Copy Utility opens (!). When I click that window off the Reader installation window closes as well. I have tried not closing off the Epson window for 5-15 minutes just in case the installation might proceed to 100%, but no success.)
P.S. Anyone who uninstalls Reader 8 or 8.1.2 before trying to install Reader 9 will find that Adobe has removed the option to download and reinstall the 8.1.2 security update. At best, and this is even if you have kept a copy of the Reader 8 installation file, you will be able to install only Reader 8 which supposedly has a security problem.
Fortunately, using System Restore, I was able to go back to Reader 8.1.2 .