Today while in the Twitterverse I followed a link @TheEllenShow posted which was supposed to take me to a video…

The link: http://su.pr/1vsyp6 which redirects to a stumbleupon URL which is supposed to be a video of Matthew Broderick trying to guess Ellen’s Mystery Word
To my Surprise I received this error message

Followed by Microsoft Security Essentials saying I needed to “Clean” my computer 🙁
Following the link again did not come back with any error at all. Has anyone seen this before? What can cause this type of behavior?
I just had the same thing happen on another site. Maybe Microsoft is having a bad day?