Assuming your PC meets the minimum requirements for MEP MX, the problem could be in your settings.
I don't have MEP MX but there should something similar to this:
File > Settings > Program
In the menu this brings up select the Playback tab. Should be a section called Arranger where you can check OFF, SLOW, or FAST under Auto scroll during playback. Make sure OFF is not selected.
Also on this tab there should be a section called Video Playback with settings for Size of video cache - highlight NO CACHE if it is not already selected.
Thanks David this still did not fix this? I got the program yesterday and I have been using previous version with no problems? I reset all the settings back to default.
So we r all on the same page----On my program there should be two yellow lines, one at the beginning and one that moves across so I can tell where I am on the video, the video plays but there is no yellow line moving across the timeline??