Can't boot from USB when DVD present

[boring97009]

Greetings. I'm trying to eject a Knoppix V7 DVD from the drive of a Dell Studio 1558. It lacks a manual eject and the Win7 install is busted (hence the knoppix DVD). I've got a USB drive with V6 on it, but when I try to boot from the USB, it starts, then switches to the DVD...meaning I can't eject the DVD.

Is there a boot setting that forces Knoppix to stay with the USB and not shift to the DVD?

For those thinking of other options, there's no BIOS setting to disable the optical drive and the only other way to get the disk out is by disassembling the laptop.

Thanks.

[boring97009]

Found a solution by creating a new partition and installing knoppix on the HDD.