FYI: No X ... oops
(CCing Carlos Carrero Gutierrez since it may be his problem too)
I did some minor system tweaks and rebooted... alas, X does not start on lenny.
Careful reading of error message pointed me to missing /dev/agpgart. My
dual boot system function works OK. So this is software issue.
# modprobe intel-agp
Hmmm... does not work.
# depmod -a
Then system reboot OK.
I do not have time to find which package or action caused this trouble
but if you find similar problem, recreating modules.dep and map files
may be good idea.