If the memory_limit is alright, then it's probably a memory limitation on the process (either apache or php). Put the following code in a file and open it's URL in the browser. You should then get an output of memory limits for the running process (if it's a linux box)

<?php
echo '<pre>';
print system('ulimit -a');
echo '</pre>';
?>

here is the reply, does this seems fine?

core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 73728
max locked memory (kbytes, -l) 32
max memory size (kbytes, -m) unlimited
open files (-n) 16384
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 10240
cpu time (seconds, -t) 150
max user processes (-u) 25
virtual memory (kbytes, -v) 83635
file locks (-x) unlimited
file locks (-x) unlimited

Yeah.. this looks fine to me. Did you ask your Hosting Provider for a solution to the problem? Maybe there's some other memory limitation?

The problem has been fixed. I had to up the apache memory to 150MB and then it accepted the save and publish. Wow I cannot believe Silverstripe use this much memory. I use it extensively saving and updating pages everyday, please advise on why this would be, and would this increase the more I use Silverstripe. This is the feeling I get from this error that it would increase the more I use Silverstripe, could this be a bug in v2.3.3?