$.post("/my_url") is ignoring "/my_url" and posting to the page url in IE7

$.post("/my_url") is ignoring "/my_url" and posting to the page url in IE7

Hi,

I have the following code working in Chrome, IE8 and FF:

$.post("/my_url", { param: "1" }, function(data) { // }, "json")

In IE7 I can see the posts on the server but they are to the wrong url ("/" in this case).

Has anyone seen this before? Any ideas what's going wrong?

Thanks,
Natalie