1) Backup all your data\n\n2) Do a fresh, complete re-install of the operating system.\n\nThere are other ways to troubleshoot it but they do not have a 100% success rate, and your system networking stack is corrupted. \nBackup/reinstall is the the most sure-fire fix.\n\nMake sure to install all updates and do all the tiresome reboots before you install any of your programs.\n\nYou likely had a malware (bad, evil software that could even steal your bank passwords) infection on your machine, so you should reformat it anyways.