Recently what appeared to a be a problem with IE 7.0 on my Lenovo T61p drove me up the wall. Every time, I would open a second instance of the browser, it would not only freeze the browser but also all the active windows on my machine!!! I later found out that it was the "Shockwave Flash Object" by Adobe that was the culprit. So overcome this otherwise annoying problem, in IE 7.0 I went to Tools - Manage Add-ons - Enable or Disable Add-ons and disabled the "Shockwave Flash Object" and voila... This action seems to have fixed my problem wherein I can now have multiple instances of IE or for that matter have multiple tab pages in a single instance of IE 7.0.