Gnome2 segv eats CPU when RAM - 1.5GB?

[supraexpress_spamyourself at globaleyes.net]

If I install only 1.0GB of RAM, I have no problems with anything. When I
install 1.5GB of RAM (all of the same chips, et cetera), gnome-segv all of
sudden chews up something like 97% (or more) of the CPU and basically
"goes nowhere". A couple times, Gnome2 would "more or less come up", but
many, if not all, of the panel icons would be gone and the 'logout' button
would not function.

Is there something (un)magical about RAM > 1.0GB?