I'm having the same issue...
Registered via Google Account, just bought the game - no issue.
Logging into the website via Google Account - no issue.
Trying to sign into the Launcher - doesn't work, getting the same error as Sexshomaru
Also @Iiunnus : It's not about the website, it's about the Launcher to install/update the game itself. You can't use a different browser there.
I have an annoying issue with the Gmail app. When I am in another program (ie BaconReader) and get an email, if I use the notification to read the email and then press back to exit, it goes to the home screen instead of my last application. Is this normal? Any fixes out there?