For unknown reasons the installer is unable to remove/replace C:\Windows\SysWOW64\Macromed\Flash\activex.vch
Delete the file manually, then try the install again. Use http://www.emptyloop.com/unlocker/ if you also cannot delete the file manually.
Thanks for your response Pat.
The file in question was not in the folder. The clean installation process included removing all files from that folder. I didn't set the folder options to show hidden files. Is this a hidden file?
I don't know if this is a hidden file or not. What I would recommend that you delete the Flash folders (in both C:\Windows\SysWOW64\Macromed and C:\Windows\system32\Macromed) after uninstalling, then try the reinstall again.