Recently an application customers of ours use required us to downgrade their current version of flash player to 126.96.36.199. I uninstalled flash player using adobe's uninstaller. When I go to reinstall flash player 188.8.131.52 using the msi installer, I receive error 1721. I have tried all steps provided in your KB regarding this. This install is being attempted on a Win 7 Pro 32bit OS machine.
How can we resolve this issue?
Did you think to try the exe instead of the msi?
Also there is a clean uninstall/install process did you try that? There is a BAT file i made which uses the adobe uninstaller and then cleans up some files on Win7 machines. Click on my name and go to the sourceforge link. Under the green button click browse all files. there is a uninstall folder with a bat file for you to try prior to re-installing it. that will remove only. You also need to be aware that IF they are using Firefox you need to re-install that plugin type as well.
IF that does not work, I have seen rogue registry entries cause issues from previous installs for machines that are not frequently updated/imaged. That is a another ball of wax to deal with. I got something for that but I as far as I know the person I wrote it for has never told me if it worked , so its not published.
Hope some of that helps