Cannot play clips in event viewer

Suddenly, I can't play clips in the event viewer without scrubbing through them first. Clips play fine in quicktime, and in timeline. If I try to play a clip in the event viewer, it won't play if i hit the space bar, the "L" shortcut, or even click directly on the play button in the viewer. However, if I scrub through the clip first, then it will eventually play. this weird behavior is not restricted to a single library, or project. I trashed preferences already and still no joy. HELP!!!!