DSL is based on a very very very old version of Knoppix, and as far as I know it has been abandoned. So your best advice might be to abandon it also, or post what you are hoping to accomplish with it and perhaps get better suggestions for other distros that are still supported that will do what you hope.

I know nothing about the boot tool that you are using, so can't help you there and that might be a good place to start. However, the error "Dropping you to a (very limited) shell." is very familiar, and I most ofter associate it with someone who has burnt the CD or DVD at high speed. I wish this wasn't the case, and at first I didn't believe it, but it is very important to burn a disc at low speed. I suggest no more than 4x.

This error could also be caused by lack of hardware support. For example, when DSL was made there were only IDE drives, no SATA drives. If you are trying to boot the disc from an SATA drive you might well be running into problems with the Linux kernel unable to find the SATA drive during the boot process. This takes us back to the first issue that I mentioned above.