This article applies to:
Unexpected data or unexpected background shows through a transparent object that is first to run in an experiment.
When the DisplayDevice object opens, it paints on to whatever memory is present in the video adapter. If the first object in the experiment has a transparent background, the contents in video memory, which can be considered unexpected data, will show through.
Update to E-Prime 1.2.
This workaround is intended only for those who are unable to update to the version of E-Prime that contains the bug fix:
Clear the screen by using a full screen, opaque, TextDisplay object as the first running object in the experiment.