Occasionally you will note a behavior where 1/8th of the student screens will display 8 times in the thumbnail (basically it tiles the portion of the screen it received). You can fix this error by going to the registry key:

 HKEY_LOCAL_MACHINE > SOFTWARE > GenevaLogic > Vision6 > Configuration > Supervision

And change the ScreenShotStripes property from 8 to 1 then restart the teacher machine. That should usually resolve the issue.  If not, please contact technical support.