Paul has a one year old HP desktop and he's having issues with his wireless connection after removing McAfee and installing a new version. Leo says he's not a fan of McAfee, or that HP puts it on the computer (called trialware) to make a little money on the side. It causes all kinds of problems like this. Here's a technote that talks about this issue: http://service.mcafee.com/faqdocument.aspx?id=TS100810
McAfee has a consumer product trialware removal tool, so if he can get to the McAfee website and download it to a thumbdrive, it can remove anything that's lingering. Leo says to just get rid of it all and use Microsoft Defender instead.
Another issue may be that the firewall is blocking his internet access. It could even be a virus that was quarantined and when McAfee did that, it stopped a critical file. Paul should try using his Windows install disc and run the repair option in the install utility. He can also run the Microsoft System File Checker. In fact, with Windows 8.1, he can press the Windows key and start typing "Recovery." Then he can run that.