The reason I don't think its a host file edit is because these edits are usually caused to redirect major sites to add ridden virus infected fakes. But on occasion people make edits simply to **** with people. So it's worth checking out.
Open Windows Explorer
Click on Tools, Folder Options, View tab
Uncheck Hide Extensions for Known File Types
Select Show hidden files and folders
Click OK
Navigate to \Windows\System32\Drivers\etc
Open the file hosts (no extension) in Notepad (for example, right-click hosts and select Send To, Notepad)
Now remove all enries at the bottom except for local host.
Let me know if that works.