Here's what I've done:

Create an "autostart" directory in /home/knoppix/.config

Create a "fix-fstab.desktop" file in /home/knoppix/.config/autostart:

Code:
[Desktop Entry]
Name=fix-fstab
Comment=fix-fstab
Type=Application
Exec=/home/knoppix/.config/autostart/fix-fstab.sh
Terminal=false
X-GNOME-Autostart-enabled=true
Create a "fix-fstab.sh" file in /home/knoppix/.config/autostart:

Code:
#!/bin/bash
sudo rebuildfstab -r
Make the fix-fstab.sh file executable:

Code:
$ chmod +x fix-fstab.sh