Hi I had a similar problem with this drive I found that I had to update the drivers for the windows software I was using. Also the ASPI Drivers. You haven't said what writing software you are using But I found I had to update Nero to get it to work properly with the drive.
If you copy and paste the following link into your web browser you will find most of these updates, also there is a download on here from Sony which will test the drive for you.
hope this helps