[ubuntu] No internet after reboot (PPPoE)

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http://ubuntuforums.org – Yesterday I installed Ubuntu 9.10 (first time in my life) and conigured internet with pppoeconf. I entered username, password and pressed "yes" and "ok" in the other windows. Anything was ok, internet worked good. I rebooted couple of times, internet was ok. Today I turned on the computer and there was no internet. plog outputted something like "CHAP authentication failed, unit [number]". I ran pppoeconf again, nothing changed, only the number became different. I thought I could be a provider's problem, but when I booted form LiveUSB and ran pppoeconf (HowTos)