Desktop Window Manager (DWM) produces, among other things, the Windows Aero theme. If the borders around open windows appear translucent (namely, icons on the Desktop appear blurred behind the borders of open windows) then DWM and the Aero theme are enabled.
DWM may interfere with the accurate presentation of short duration images in the UFOV measure and might need to be disabled in order to run UFOV accurately. If DWM is not disabled, you might notice that sometimes the images of the car or truck in the center and periphery are not shown.
The software should disable DWM automatically. If it does not, you can disable DWM by following the instructions listed