We are having the same problem presenting videos on an new HP (core i5) running Win 7 and MediaLab 2008. We have also tried various versions of the video format (.avi, .wmv) and treating the video as an event vs. an item in a questionnaire with no success. The videos run completely, but at the end the screen is gray with empty black box and no way to proceed to the next item in the study.
Any solutions? We don't want to revert to XP.