Why wont my DVD burner burn a DVD? please help?

i have windows vista, im trying to burn a movie i made to a dvd to watch on a dvd player, i used windows movie maker to make the movie and using windows dvd maker to burn the movie. fist of, it takes forever for it to go threw the encoding process and when it FINALLY gets to about 70 something, the disk starts up, ejects, and i get a message saying WINDOWS DVD PLAYER COULD NOT FINNISH, TRY ANOTHER DVD OR MAKE SHUR YOUR DVD PLAYER IS CONNECTED. it should be connected though, i can watch movies on it, and burn music just fine... can anyone help me with this,,o and it use to work fine i dont know why its doing this now, maybe becuse i reinstalled my vista? THANK YOU FOR ANY HELP