You may need to enable viewing of hidden files and folders:
1. Click Start.
2. Click My Computer.
3. Select the Tools menu and click Folder Options.
4. Select the View Tab.
5. Under the Hidden files and folders heading select Show hidden files and folders.
6. Click Yes to confirm.
7. Uncheck the Hide file extensions for known file types.
8. Click OK.
and delete it.
Download a new hosts click here
Restart your PC.