While you still have time, double check all your settings in Sony Vegas. Make sure that the video is set for complete compatibility. If MP4 absolutely is not working when you do the encoding, switch to AVI or WMV. When you wake up tomorrow morning, copy all versions of the video, including the messed up MP4 files to a USB thumb drive, if you can. If not, fit only the new version. Before doing any further operations in Sony Vegas, restart your entire computer, disable your anti-virus temporarily, and allow the encoding to run. If the encoding STILL does not work, something is wrong with Sony Vegas and there is nothing you can do with, given the time constraint. But, by at least bringing the files in, you are showing that a great deal of effort did go in to encoding them correctly. If you have your teacher's e-mail, you might want to tell him or her, that you are having some technical difficulties right now, so that tomorrow, there can be no surprise.