Everytime I install SL it gives me the message "Media plugin cef is missing".

[Rolig Loon]

If you are repeatedly reinstalling without removing the viewer's hidden files -- which include the CEF plugin, I believe -- then you are reinstalling the same damaged copy over and over again. The cef plugin is a feature of the newest Linden Lab viewer (4.0.0.309247), intended to solve most of the problems that SL residents have had with Adobe Flash and QuickTime over the years.  If your copy was damaged on download, you should be doing a Clean Reinstall >>> https://community.secondlife.com/t5/English-Knowledge-Base/How-to-uninstall-and-reinstall-Second-Life/ta-p/1375231

[Rolig Loon]

If you are repeatedly reinstalling without removing the viewer's hidden files -- which include the CEF plugin, I believe -- then you are reinstalling the same damaged copy over and over again. The cef plugin is a feature of the newest Linden Lab viewer (4.0.0.309247), intended to solve most of the problems that SL residents have had with Adobe Flash and QuickTime over the years.  If your copy was damaged on download, you should be doing a Clean Reinstall >>> https://community.secondlife.com/t5/English-Knowledge-Base/How-to-uninstall-and-reinstall-Second-Life/ta-p/1375231