I'm using UBCD 5.0.3 on USB, the boot is very fast, nothing to complain about

I'm using it to erase a bunch of computers' HD, and when using DBAN it shows me 2 erasable devices :
- the USB key
- the HD
If I only select the HD the program is terminated but I can't see the error as I don't have a floppy drive. The only way to get it all work is by selecting both drives (therefore it erases the key as well, which is not convenient at all....
Have you ever noticed this issue? How can we avoid it?
Thank you
