Click-N-ship not processing a label order

Earlier today, I was preparing a label for a box heading up to Canada. Everything was moving along nicely right up until I had to specifiy the service I wanted applied to the box (i.e. what kind of box I was shipping in, etc).

The problem is that I can not get to that screen. Each time I pressed the blue button to proceed with the label order, I kept encountering this message:

An unexpected error has occurred. Please try refreshing the page.

Needless to say, refreshing the page does not correct this problem. I am using Google Chrome, and up until today, I had no problems with Click-N-Ship.

I also find it odd that this problem only seems to be happening with international orders. Domestic labels are created without any difficulty.