I wasn't able to reproduce your issue.  Are you able to reproduce your issue consistantly?

Couple of things you might want to consider:

 - How many browser windows you have open.
 - What background processes are you running.
 - Did the browser freeze for a short period and recover or did it crash.
 - What other programs are running that are intergrated with IE?
      - Windows / Windows Live Messenger
      - Any Windows Office product
      - Most Norton Products

You would not believe how many products are integrated with Internet Explorer.  This can cause memory management issues.

Regradless of what browser you choose in the future for browsing, I find that IE tends to be the most compliant with web development standards.