[ppc] lots of buffer i/o error at start up

[2g]

it is quit like my iBookG4 itself has a problem
but let me try this post, please

installed 6.10ppc to this machine and now have dual boot environment 
with osx
since exchanging the sony-oriented-volcano-battery to the other one 
with apple
hdd (or motherboard) started behaving weird and
did a plenty of erasing and re-installing the osx
during the repartitioning process
came up with the idea to install ubuntu too and downloaded the iso

the disk first aid says "nothing is wrong" with any volume
but when booting the ubuntu's cd
lots of "buffer i/o error" came out and because of that
booting itself got delayed quite long

same thing happens when booting the installed ubuntu from the hdd
and most of the problem it reports about the hdax is
about the one formatted for osx (hfs+?)

both osx and ubuntu runs okay
after it gets booted

some one told me
that i should have done more clean up of power management thing
before and after setting the new battery
and with that done osx seems to become normal
but ubuntu booting reports the same thing all the time

what's maybe going on?

have to look for a way to make yaboot choose osx
as the default booting os

thanx

2g ---
http://micro.ispretty.com