Is there any way to configure Microsoft Internet Explorer so that one window can’t steal focus from another one? I’m tired of being interrupted in the middle of something.
When are you getting interrupted? Do you mean by popups? Or is it more a matter of opening a new window, waiting for a page to load, going back to your original window and then getting “interrupted” by the new window once it’s loaded?
If it’s just popups, try a popup blocker like Google Toolbar. I’m not aware of any window focus settings in IE.
I am sure the Mozilla Mavens will be in shortly to tell you how to live an interruption-free existence with Firefox, tho 
It’s not popups; it’s the second thing.
Changing software is not an option for me. There are higher powers who institute these things.
In fact, in order to install any kind of software, we have to call our I.T. department to do it for us. They also have rules about what they will install. They are very reluctant to install anything that isn’t on their “we support” list and they will refuse to install anything they haven’t heard of, especially if it’s a third-party product.
I’m not aware of any way to do this. Even Microsoft’s orphanware app TweakUI won’t prevent one IE window from stepping on another, despite the setting “Prevent applications from stealing focus”