I love tabbed browsing, plain and simple. I just can't live without it. There is one thing, however, that's become an issue. For simplicity in explaining the situation, I'll use a scenario that we all use (or, at least should be using): Microsoft Update.
First thing's first, make sure you have 2+ tabs open. Next, browse to Microsoft Update, select at least one update to install, and start the installation. When Microsoft Update starts the install, a dialog box appears. As it should, this dialog box doesn't allow you to interact with its parent page. Unfortunately, it doesn't let you interact with any page. This should be changed so dialog boxes only limit your access to the web page and not the entire application (IE). Primarily, I want to be able to switch tabs and do other things while the download/install is in progress. Currently, to do this, I must open Microsoft Update in its own window.