DVDSP will simulate, but not burn

I share a video editing station with a co-worker; we each have our own separate log-ins. I don't have any problems using Quicktime movies in DVDSP & getting them to simulate & then burn. He can get the movies to simulate fine, but keeps getting error messages when the DVD starts to burn (I'll write down the messages next time he tries the program; we were in a rush this morning to meet a deadline). I have noticed my program opens with the Choose Application Defaults dialog, & his doesn't, so I'm wondering if it's a setting issue. I should also say we're using the same copy of DVDSP, but using separate log-ins, & of course only using it one person at a time. tia.

david