Toshiba laptop won't boot "live" DVD

I've been trying to demo Linux on the missus's Toshiba laptop to no avail. I've gotten into the BIOS and set the boot order to DVD first followed by hard disk. When powering up the system, there is a brief flurry of activity on the DVD drive but ultimately goes ahead and boots Win7 from the hard disk. The Live DVD I'm trying to boot is a Debian Live DVD that I've previously been able to boot from on a system that doesn't have any Windows presence at all. (I haven't yet downloaded any other live ISOs to test with.)

Is there a trick to get Toshibas to boot from the DVD drive?

TIA for any tips.