It may be that the Adobe servers have been misbehaving (again), and it will work in a bit.
It may be that your ADE has got itself into a half-authorized state.
Try ctrl-shift-D to deauthorise, restart ADE (possibly not necessary), and try again to authorize.
You may need to disable your firewall temporarily while you authorize.
You may be best of reverting to v1.7.2; which seems a lot more reliable than v2.0.
Thanks! The deauthorize, reauthorize process worked for me. I appreciate the help!