Welcome.
Just a guess, but 3.3 didn't have DMA on by default and I think 5.1.1 does. Try knoppix nodma at the boot prompt.
Troubles with boot 5.1.1 Knoppix. There is followin in the screen:
Welcome to the KNOPPIX live GNU/Linux on CD!
Running Linux Kernel 2.6.19.
Total Memory available: 125092kB, Memory free: 117776kB.
Scanning for USB/Firewire devices... Done.
Enabling DMA acceleration for: hda [IBM-DBOA-2513]
Enabling DMA acceleration for: hdc [CD-ROM CDR_U200]
Lookin for CD in: /dev/hdc
... and nothing more except sound of working cdrom. Box is P1 Dell Latitude notebook. Very old Knoppix (3.3) works fine. Any ideas?
Welcome.
Just a guess, but 3.3 didn't have DMA on by default and I think 5.1.1 does. Try knoppix nodma at the boot prompt.
---
Verifying of md5 checksum and burning a CD at slow speed are important.
It works fine, thank you.

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