In order to calibrate and profile a monitor, the software must be able to download correction information to the computer's graphics/video card. This modifies a correction Look Up Table (LUT) in the video card every time your computer is started or your profile is loaded. The video card, driver and operating system must allow this to be done or monitor profiling will not work. The answer varies depending on your system:
As a requirement for running on MacOSX, all video cards must accept a downloadable LUT.
Download our "LUT tester" and instructions to determine if your Windows system is compatible: