In older Flash versions, for example, plugin version 10.3.183.18 on Windows, the file name would simply be "NPSWF32.dll".
To see if the Flash plugin is working and what version is being used, visit one of these pages: If Flash is not installed, this may trigger the Plug-in Finder Service, which you can use to download and install the Flash plugin on Windows (see below).
Plug-ins can cause crashes and hangs and may contain security vulnerabilities.
Visit Adobe's website for information on security and stability issues affecting Adobe Flash.
Note: On Windows, the Flash plugin is detected via plugin scanning.
If you have installed the Flash plugin but it does not appear in the Add-ons Manager, open about:config and make sure that the preference has not been set to "false" (if it has, right-click on it and select Reset to set it back to "true").
At time of writing, the Plug-in Finder Service is triggered but fails to install the Flash plugin on Linux or Mac OS in Firefox 3 and above (you will need to manually download and install the plugin).