Activation is normally a very quick and simple process. The most common cause for error is the presence of a Proxy Server configuration. One possible error resulting from this is that below:
To get around this, you may either provide your proxy details in the Activation dialog, or make use of the offline activation option.
There have also been reports that some web-filtering applications such as "Proxomitron" have stopped activation from succeeding. If you are running such a program and have any problems, please try pausing/stopping the program during the activation process (no need after activation has completed).