Having trouble installing flash player onto vista for the first time. Program downloads but when I click on it to open, nothing happens. Tried many different sources for the download. My web browser is firefox, but I tried it on IE and it didn't work either. Thanks for any light on the matter.
This may be due to a signing certificate issue. The onlinie installer uses the SHA256 certificate, which may not be compatible with a computer that is running Windows Vista SP2 or Windows Server 2008 SP2.
If this is your setup, head over to the Microsoft Support page to download an update for your operating system.
Alternatively, you can try the offline installer posted at the bottom of the Installation problems | Flash Player | Windows 7 and earlier page in the 'Still having problems' section, however, there is no guarantee that it'll work. If it doesn't work, you'll need to you'll need to update your system according to the information at https://support.microsoft.com/en-us/kb/2763674.