[charliesome]

I'm also a Chrome user on OS X, but I can't reproduce this... Maybe check if it's one of your extensions?

[billturner]

I've disabled all extensions, and the same thing happens. In fact, there's also a warning that "This site is attempting to download multiple files. Do you want to allow this?"

I'm on Mountain Lion, Chrome Version 23.0.1271.101

Edited to add: This happens on page load, before there is any interaction with the page.