segfaults happen all the time for any number of reasons.
you do know there is a bug in apache right now that will cause children to die, right?
http://httpd.apache.org/info/securit...n_20020620.txt
it's not just for windows either. however, the *nix versions don't completely die, just shed off children processes i believe.
i've created segfaults by using messed up libraries with php functions needing things like GD and such. i've never seen a tie to a segfault in a program to a physical memory error. the programs would not continue to load using the same memory address irregardless. if you have bad memory you'd probably see a lot weirder things than just some child apache processes dying..