I've been burning some dvds on and off for the past couple of weeks. Every now and then it'll shoot the disc out (as it does when it's finished) but the disc doesn't work on my dvd player. It works fine on the computer. When it does this the idvd screen says current operation done but the burning wheel is still spinning and nothing else will click on. My past three burns have all done this. All in all about a dozen burns have worked and about 6 have not. Any thoughts on what the problem might be?