A fix for this problem is to add swap (i.e. paging) space to the instance.
Paging works by creating an area on your hard drive and using it for extra memory, this memory is much slower than normal memory however much more of it is available.
To add this extra space to your instance you type:
sudo /bin/dd if=/dev/zero of=/var/swap.1 bs=1M count=1024 sudo /sbin/mkswap /var/swap.1 sudo chmod 600 /var/swap.1 sudo /sbin/swapon /var/swap.1
If you need more than 1024 then change that to something higher.