chap authentication failure

FIXED, please close thread

chap authentication failes after i removed following files

/Library/Preferences/SystemConfiguration/com.apple.airport.preferences.plist
/Library/Preferences/SystemConfiguration/NetworkInterfaces.plist
/Library/Preferences/SystemConfiguration/preferences.plist

I am only using ethernet via cable, no wireless

I did this to fix the
"Your network settings have been changed by another app" problem
with Security Update 2008-06.

I made a new pppoe configuration for the ethernet. pretty sure login/password is corrent ( 10 retries ! )
this gave me new files in /Library/Preferences/SystemConfiguration/

But the /var/log/ppp.log gives a CHAP authentication failure.

I have read that "Security Update 2008-06" was password related.

Any ideas what i can try next?