Seems like Microsoft decided to continue the Vista way for unicode programs, so only one unicode language will be supported at any time by going to the settings for system locale.

For me, i'm running CJK programs concurrently, so i need another solution.

The ancient old AppLocale still works for Windows 7. To install,
1. Press the windows key
2. Type 'cmd' without the quotes, press Ctrl + Shift + Enter
3. The above steps will launch the command prompt in administrator mode, the UAC will prompt you, permit it to continue
4. Navigate to the directory where the apploc.msi is locate and start the setup :D

The following link is a patch to the AppLocale to remove the nag screen