Just going to throw this out there folks, as i think this is the way i did it a while back. Hopefully i know what im talking about, lol. In order to download an older version of flash, you can go to this thread here, locate the version you want to use, and save it to your desktop. You may need to scroll down to find the older versions:
http://helpx.adobe.com/flash-player/kb/archived-flash-player-versions.html#main_Archived_versions
When you have that saved to your desktop, then go and download the flash player uninstaller. As far as i know, the system will tell you that you have a newer version, and will not let you go to an older version unless the flash player has been uninstalled first? Save this to your desktop also.
http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html
When you have the uninstaller downloaded, uninstall the version you have, and then install the old version you saved from the 1st link that is saved on your desktop.
This may have been mentioned already, as i didn't read the whole thread. And please only try this if you know what you are doing, as i don't want to be responsible for anyone's system going t*ts up.
I would like someone who knows what they are doing to confirm if this is possible, before anyone tries it.