I encountered an interesting IE bug/feature today worth mentioning: When running a page, I received the error message "Internet Explorer cannot open the Internet site, Operation aborted." This perplexed me largely because the page seemed to load, and behaved very kindly in Firefox.

The problem was a single offending line of JavaScript:

document.body.appendChild(someElement);

This line was positioned within the body tag, so it would execute before IE finished rendering the body. Instead of saying "You cannot use script to add to the body tag until the page is fully loaded," the browser provided the cryptic "Operation aborted" message.

I hope this helps.