Nero 2014 Platinum pixelation problem

I have been using Nero 2014 for quite a while with no problems. I have always used Verbatium BD-R #97457 and everything has been fine. But here lately I have been getting a lot of pix-elation. When I import a mp4 blu-ray file in Nero to burn I preview the movie before I do anything with it and it has pixels. When I just play the file with windows player everything is fine. I have tried it on different computers thinking it might be me video card, but it does the same thing. I use NERO VIDEO in the "EDIT and CONVERT, Create and Export, and pick Blu-ray Disk, Import File, click on the file, then open. From here I click on the play to observe the file and I see a lot of pixels showing up in the movie (mp4) but no pixels if I just play it, without running Nero.