Why does Internet Explorer block all my pop-up windows?

First off, great to hear that you're enjoying your time with Movable Type. I have used it for years and still find it the best blogging tool for my work, even as I'm surrounded by Wordpress fanatics. :-)

I know what your problem is with MSIE (Internet Explorer) too. It's a security feature, actually, trying to protect you from stumbling onto the wrong site and being overrun with advertising popups. You want this feature enabled, you just need to make sure that your own site is given permission to slip through the net.

This is done by launching Internet Explorer, then choosing Tools --> Internet Options..., then click on the Privacy tab:

As you can see, the lower section is "Pop-up Blocker". You want to click on "Settings..." here so you can make the necessary changes:

What you want to do is type in the domain name of your own domain (in my case it's "www.intuitive.com" for the backend):

then click on the "Add" button. That's all you need to do. Choose "Close" and "OK" and you'll find that the window now pops up properly, even as other sites have their pop-up windows blocked.