I am using Fancybox v.2.1.2 in Wordpress (not a plugin). In IE7, I have the loading but it does not opening anything at all.
Here is my JS code
I am afraid that this is a bug (it's not your fault, it's not your code).
I have contacted directly the developer and he confirmed to me that the issue is expecting to be fixed in the next commit.
You may rollback to version v2.1.1 in the meantime.
UPDATE : Fancybox v2.1.3 has been released
Changelog Version 2.1.3 - October 23, 2012
I find the bug ... not in Fancybox but into IE7, IE8, and IE9 !
If you create an iframe with a page that contain the following CSS, then IE do not display the page :
html { position: relative; }
If you know the webmaster of the destination page, ask him to remove this CSS declaration, the display of it's page should not change ... otherwise, no solution to my knowledge!
That's all !