Vista Error Code 0×80240016 While Updating Windows Defender may be a Skype Problem
This error code 0×80240016 happened to me while I tried to update Windows Defender. After some searching I found that it may be a problem with Skype and its associated plugins for Firefox and IE. When I clicked on the windows defender update icon in the lower right of the screen vista admin did not popup and ask if I wanted to OK this.. Only after I disabled the Skype plugin for Firefox then clicked on the lower right screen icon in the tray that the admin screen appeared then I clicked approve and windows defender updated with no problem.
Maybe I just got lucky, but I hope this might help other people with the error code 0×80240016 problem. This may be an Access Denied. Meaning You do not have sufficient permissions. Be sure you are logged on as an Administrator. I was already logged on as admin but it did not let me update the first time but it did the second time. If anyone else was able to fix the 0×80240016 error code problem please post a comment.
Other possible fixes to this are:
Reboot (log on as admin)
Try Updating again.
Uninstall Skype