People be very carefull with IBM laptops !
I know IBM got series of laptops that got default encrypted harddisks.
The encryption is hardware encoded. (a chip beside the ide-controller).
So be very carefull when testing knoppix (or any other livecd) on a IBM laptop. It IS NOT INCLUDED in the warranty if you f*** up you HDD !.

Maybe it's the case for this laptop ?

If you wanna persist try booting with a cheatcode that doesn't search and automount your HDD ?