Hey man. I have had this happen to. Mine happens after I render my sequence. Video speeds up to exactly 150%. You need to go under the sequence tab, and go to settings. In there there is a section under render control for frame rate. Make sure that this is at 100%!!!!
I have been trying to figure this same problem out for over a year now, and I see that this is an old posting. If you are still having trouble, I hope this helps!