This came up before on the previous forum, check out this link and see if it helps you. If firewall software is blocking Muse from contacting Adobe, that could cause such this kind of error message.
Check that your Firewall and Antivirus software will allow connections to Adobe's servers.
As Morgan also indicated, this error can be caused by your firewall settings, antivirus or spyware/malware prevention software. Muse needs to be able to create an https connection to Adobe to verify your AdobeID. If firewall or spyware/malware prevention software is blocking Muse from creating such a connection that could cause this error message.
Please try disabling any firewall or spyware/malware utilities let us know if this resolves the problem.
Sorry but none of your solutions work. I disabled everything that had to do with firewalls and anti-virus and i'm not behind a router with a firewall either. I also went into my firewall settings to make sure to allow Muse but still it does not recognize an internet connection. I use AVG so if there is some special setting that I'm missing or if anyone can be more specific about firewall settings that would help because nothing is working so far. I'm not even getting to see the screen try to sign in to my AdobeID on Muse.