The first thing I noticed about RH 6.1 (both with the ISOs
and the RH disk) was machines that have always correctly
noted and handled my memory no longer knew how much memory I
had. To fix this you modify /etc/lilo.conf (preferrably
before upgrading otherwise you get to reboot) with the
following line (with your memory size)added to both "image="
sections and then issue the "lilo" command to activate it.