CANT ACCESS OR SAVE HOSTS FILE =

Caused by non admin permissions;

Solution; 

A, Check file is not read only (right click hosts & tick the read.write box).

B, Right click the hosts file and select properties, security, edit, your user, 
   take full control by ticking the full control box, click apply. 
   
   In XP to see the security tab do this;
   1, Launch Windows Explorer or My Computer.
   2, Click on the Tools at the menu bar, then click on Folder Options.
   3, Click on View tab.
   4, In the Advanced Settings section at the bottom of the list, clear the tick 
      on the use simple file sharing check box.
   5, Click OK.

C, Use the one (swap) in the HOSTS SET-UP folder.

D, 64bit users start internet explorer or my computer and type;

   C:\windows\system32\drivers\etc

   into the address bar and the hosts will appear.