I'm posting this here as a public service since this took me quite a while to get resolved.
After upgrading to Windows 7 (and to Internet Explorer 8 along with it) I ran into quite a perplexing problem with Flash Player 10.
My Adobe Flash Player 10 ActiveX plugin for Internet Explorer had stopped working and all of the suggested solutions listed on the Adobe website and around the internet were not working.
I tried uninstalling and reinstalling the player. I tried running the SubinACL tool from Microsoft to reset registry permissions. I tried using the standalone installer instead of the web download installer. None of it worked.
It seemed that the installer was having trouble registering the Flash10c.ocx file that is required for the player to function.
I ended up having to manually change 1 registry permission and the installer ran correctly and everything worked fine again.
The key in question was HKEY_CLASSES_ROOT\TypeLib\{D27CDB6B-AE6D-11CF-96B8-444553540000} and I had to modify it so that local\Administrators had full access.
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