When trying to connect to OpenVPN either via OpenVPN GUI / TunnelBlick / Linux 

If you see the following errors in the "Status/Log" entries 

Thu Jan 06 22:44:58 2011 Cannot load certificate file username.crt:
Thu Jan 06 22:44:58 2011 Cannot load private key file username.key

This means that the username.ovpn file cannot find the path to your username.crt or username.key file.

The follow files should exist (extracted from the username.zip file sent upon first payment)

username.key
username.crt
username.ovpn
ca.crt
dh2048.pem 

In order to resolve this please make sure that all key files from the zip file and the .ovpn files are in the same directory.

Windows: C:\Program Files\OpenVPN\config\

Mac OSX Tunnelblick: ~/Library/Applications/Tunnelblick/Configurations

Linux: /etc/openvpn/