1. If installed - uninstall the current copy of OpenVPN.
2. Download the installer from one of the following links::
   
   http://openvpn.net/release/openvpn-2.1_rc19-install.exe
   
3. When its done downloading
   
   Rt-Click Installer>>Properties>>Compatibility>>
   X Run this program in compatibility mode for:
   ---- Windows Vista
   
   Privilege Level:
   X Run this program as an administrator
   
   Then Click Ok
   (see image below)
   
   
   
   
   4. Now run the installer

Tip: Set also under properties in the OpenVPN GUI "run this programm as an administrator"