Some more ideas--and questions:
1. You mentioned Corel DVD Movie Maker. Did that come installed with your laptop or did you install it later?
2. Do you also have another program such as Roxio or Nero (or both)?
3. Did you ever use the software that came with Toshiba for making DVDs or have you only installed and used the Corel program (which version?)
I ask all of the above because I just read that sometimes one program will interfere with another one and "hijack" the drive, making it not respond when the other program is used. Please list all DVD-creation programs that you have installed and the versions.
You might want to try a clean boot as described in this Microsoft article: http://support.microsoft.com/kb/929135
It is a bit of a guess and check process but maybe it might enable you to eliminate some conflicts that may not be evident.