Hey, looks like there's a small glitch with the iTunes Music Store. Here's a quote from the report:
[W]e've uncovered one last little issue ourselves: if you try to purchase Mario Lanza Sings Christmas Carols, Andy Griffith: Just As I Am-- 30 Favorite Old Time Hymns, and Mobstability by Twista & The Speedknot Mobstaz all within the same 90-minute period, your Mac will actually punch you in the face. It is currently not known whether this is a bug or a feature.