Knoppix Question

As stated in an earlier message, I'm in the process of updating my system. At present my install of SuSE7.1 won't recognize any of the new AGP cards I've tried (in the process I've settled on the ATI Radeon 9200se) so I've been booting with Knoppix. When I try to use any of my installed files like mozilla and the mail reader Knoppis tells me things like: "You do not have enough permissions to read file:/mnt/sdc3/home/dcjohan". Can anyone tell me how to get into my files so I can run the installed programs on the drive? tia, dave