EDIT: The "popular posts" (Blog Window) widget is now working fine again, and the AffiliateBrand website is also back online!
It seems that this was just a temporary glitch in the system, though all services are working perfectly now including the Analytics Wizard statistics, so check your inbox if you've been waiting for your blog stats as you've probably received your daily email a little later than usual.
Personally, I'm relieved that the widget is working properly again, and am prepared to suffer a few hiccups for the benefits this widget offers myself and my readers. A popular service such as this is bound to experience difficulties from time to time. Even the mighty Google occasionally slips up, as we experienced when we were unable to upload images (and occasionally when we are unable to load our blogs!).
If I do find out what caused this problem and whether it's likely to happen again, I will of course let you all know about this.