Adobe tn_19166 error fix
If you can't get the Adobe Flash Active X plugin to install on your computer due to the error tn_19166, don't bother contacting Adobe. They will lead you on a wild goose chase which will do nothing but frustrate you.
After trying many things, including uninstalling all Adobe products, running some CS4 Cleaner, running some Microsoft tool, and other nonsense, I found a fix on FixYa.com.
Here are the instructions:
Open a cmd window.
Go to Start -> Run -> type cmd
Make sure you're on the main drive, usually C. Type C: if you're not.
Then type the following (you can cut and paste this):
secedit /configure /cfg %windir%\repair\secsetup.inf /db secsetup.sdb /verbose
This will run some sort of repair. Initially it will seem like it'll take hours to complete, but before long the progress amount rises fast and, for me, everything was over within 5 minutes.
Then I ran the Adobe Installer for the Flash Active X plugin and in almost no time at all everything was fixed.