oui j'ai eu le probleme. Ils expliquent ça sur la page d'octagon
http://www.octgn.net/downloads.php
Citation :
•The link only works if you have at least .NET 4 installed. If you don't have it (it should be listed as "Microsoft .NET Framework 4 Client Profile" in your add/remove programs control panel), you can install it from here: .NET 4 installer
•The link works in Internet Explorer. It works in FireFox as well, provided you have the ClickOnce plugin. If you already have .NET 4, this plugin was automatically installed in FireFox.
il faut installer .net framework 4. Clique sur leur lien, install, redemare.
Ensuite j'ai plus eu le probleme