Re: help on fixing sudoer
Your best option would probably be to boot from the live CD, mount your hard-disk partitions and then edit your troubled /etc/sudoers file using visudo.
Using visudo will warn you of errors before saving. Don't save the file if there are errors - as you've seen it causing a bit of grief but, as long as you've physical access to the box it's not too big an issue.
AMD Athlon 64 X2 4800+ / ASUS M2NPV-VM / Corsair 8GB PC2-6400 / 4.5TB RAID10-LVM / 3TB LVM - Ubuntu 11.04
Asus Eee PC 1000HE - Crucial 2GB PC-6400 - Ubuntu 11.04