For the last few months have been getting the below
error message. This is only occasionally and not sure its always the same site.
What is the cause?

Warning Unresponsive Script

A script on this page may be busy, or it may have stopped responding. You can stop the script now,
or you can continue to see if the script will complete.

Script: http://l.yimg.com/zz/combo?nn/lib/me...yui_3.4.4.js:1