Mike's wife was on a site a few days ago and now there's a search bar in Internet Explorer that they don't want. Leo says it's likely a piece of malware, but it may simply an issue of just removing it from add/remove programs. But it also could be something more malicious. There are things called "zero day exploits" where Microsoft announces a bug they are fixing and hackers took advantage of it the same day it was discovered. If he can't run Windows update, then it's something that needs to be removed. He won't be able to run system restore either if that's the case.
At this point, the best thing to do is backup the data, format the hard drive, and then reinstall and update Windows from a known good source. He could try fixing it with something like MalwareBytes, but he will never know how badly infected he is. It's best to just start over from scratch.