Preparing a new installation of Ubuntu and finding that you can’t load Adobe’s Flash Player? Turns out this is because Adobe released a new version and the Ubuntu downloader isn’t synchronized with the file on Adobe’s website (basically it says that there’s a checksum mismatch; bug report here). If you want/need the latest version (9,0,115,0) before the updated version of the downloader posts to the official repositories, just follow the instructions in this post. Then test here. That should do the trick :)
Adobe’s Flash Plugin not installing in Ubuntu for you?