http://board.tera.gameforge.com/board2-tera-en/boa rd687-en-forum-archive/67264-tera-black-screen/Disable the 3GB switch on Windows Vista and Windows 7 (32-bit)
• Right-click on Command Prompt in the Accessories program group of the Start menu. Click Run as Administrator.
• At the command prompt, enter "bcdedit /deletevalue IncreaseUserVa"
• Restart the computer.