1. Boot with Knoppix
2. mount /dev/sda1 /mnt
3. vi /etc/shaodw
4. i
5. kill the string between the first and second :...
for example: user:$1$pM8HYEMB$Cx0yiRM4pj2Ty4lFBWuy4.:12038:0:99999:7::: becomes:
user::12038:0:99999:7:::
6. ESC :w Enter
7. cd /
8. umount /mnt
9. reboot
10. login with user and just press enter on password.
11. enter passwd and change the password.
12. you're done!