try keeping eth0/PPPoE off when booting up
I use a PPPoE connection myself and the only way I could get it to work on Mandriva LE2005 is by having eth0 configured for PPPoE in the control panel but TURNED OFF during startup. I then go to the Network Status icon in the (KDE) toolbar next to the clock and manually turn on the connection whenever I need it, and then I open my web browser.
My apologies if I don't have the names of the Linux/KDE items correct - I'm new to Linux and I'm currently surfing in OSX/Firefox for my dualboot iBook.
1.2 GHz iBook G4 (PPC; early 2004)
Mac OS X Panther 10.3.9
Mandriva Linux LE2005 PPC
Linux web browser: Mozilla 1.7.7