red banner on top of the page about other domain javascript

i'm getting a message in a red banner in the top of the page saying "Physics requires external JavaScript from another domain, which is blocked or failed to load"

I've never seen it before. what is it about?

EDIT i'm using google chrome, for some reason i can't comment (it says 2 more to go..)

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What browser/OS are you using? – mbq May 6 '11 at 14:08
The "n more to go" is the number of additional character to reach the minimum. – dmckee May 6 '11 at 15:26

The message shows up when jQuery isn't available, which ususally happens because ajax.googleapis.com is blocked by things like NoScript.