I have Windows 7 Home Premium and IExplorer 9 Beta on my Acer Aspire laptop and both seem to run OK with the exception of Adobe Flash Player.
When I click on many videos I am told that I do not have the correct Adobe Flash Player and I offered a download of the appropriate one.
I download and install the player and I am told that all has been completed successfully. I have then, even though not suggested, restarted the computer.
However after a restart of IE9 I get the same error message so the player has NOT been installed.
I also have the latest Firefox and the player works OK here.