Andy,

I am having the same problem. When I click login nothing happens. The screen is blank. When I click guest my web browser automatically opens and redirects to NetAcad's web page to sign up for a packet tracer course. I tried installing Packet Tracer from my Windows 10 pc as well as a Windows 8.1 PC to no avail. I believe the problem lies in Cisco Packet Tracer version 7.

*edit: I have also tried using different default browsers (chrome/IE), and disabling my firewall. Re-downloading the program and restarting my computer. Using the windows compatibility tool on windows 10. Nothing has worked thus far.