Can't burn dvd's with Ashampoo or other, but

For some reason Ashampoo Burning Studio, or RecordMax burning studio and others will not burn my data dvd. This is the first time this has happened. I have no problem burning an .avi to dvd with convertxtodvd, but now, I get errors telling me write or burn failed when I use other programs. I don’t even know where to start. It worked fine a couple weeks ago, now all of a sudden it will not. Have WinXP pro sp3, in fact I just noticed that when I insert a blank dvd, the system registers it as a cd. But, then why would convertxtodvd not have any issues as well ?