I am triple booting Windows Vista, Ubuntu 12.04 desktop and a Fluxbox based on Ubuntu 12.10 mini-iso. Vista was installed first, then I installed Ubuntu 12.04 desktop and then Ubuntu 12.10 Fluxbox. The Ubuntu 12.10 Fluxbox installation booted as default, which was my intention. All the systems get updated regularly. Sometimes after a dist-update in the Ubuntu system which isn't booting as default the default boot changes to that system. So sometimes the GRUB boot-order changes from Ubuntu 12.10 Fluxbox as default to Ubuntu 12.04 desktop as default, a number of dist-updates later it changes back again. This behavior happens repeatedly, what causes the behaviour only sometimes is not clear.
It seems like there are two grub.cfg files (resposible for generating the GRUB startup menu as I understand it) ,one generated by Ubuntu 12.04 desktop and one by Ubuntu 12.10 Fluxbox. During boot one of those files gets read. Which one is used changes sometimes after the updates. The updates are not release-updates (e.g. 12.04 -> 12.10).
Is there any way to prevent this behaviour?