Stuck on adding ISBN

I'm trying to add ISBN 0201793032 to my list, but it simply gets stuck trying, never loads the page and thus never tells me it added it. Almost as though it's waiting on data elsewhere or stuck in an infinite loop.

Update on this -- I let it sit for a while and it finally came back only with the ItemResponse XML tags, repeating them about 100-150 times. (no layout or anything, just those tags.)