Plop's OK, Knoppix's NOT

Re: Knoppix 7.0.3 LiveUSB/CD
Via Technologies VT6202 4 Port USB 2.0 Host Controller

Hi,

With Knoppix LiveUSB plugged into a VT6202 port, Plop detects it and gets the boot screen displayed to enter cheatcodes, then this boot error gets trapped:
Could not mount disk to /mnt-system. Starting debugging shell . . .
SH: Can't access TTY; Job control turned off
/#
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link

Q: How can the linux modules ehci_hcd, ohci_hcd, uhci_hcd and usb_storage modues be unloaded separately, to troubleshoot?

Regards,
luther