I ran across this problem after doing a reset on IE7 under the Advanced Tab on Options, my green border stopped displaying.
Go to Tools…Internet Options
Under the Programs tab…go to Enable or Disable Browser Add-ons installed in your system
Click the drop-down menu arrow
Make sure Comodo Verification Engine is Enabled
Close out IE and re-open it
Your green browser border should display again.
This fix also works in IE6 since one of my buddies was having the same problem.
Hope this helps someone.