Re: It's Grub Again???
You have been working under some misunderstandings. When Grub2, or its predecessor Grub, is installed it writes some components to the Linux partition and a component to the mbr of the drive designated. This component written to the mbr does little besides take the hand off from bios and then provide boot functionality based on choices for configuration that you make, by loading components from the Linux partition. I doubt that you have done any configuration by the sounds of it so the default configuration is in place.
When an update that includes a kernel update happens, grub must be updated to know about the new kernel version but that happens to the part of grub in the Linux partition, not what is in the mbr. If an update happens that changes grub version, such as would have happened to you at some point (I think when you updated to 10.04) when Grub went from Grub legacy to Grub2, the Grub installation program will be run and prompt you for where to write the part of the program that normally goes to the mbr. You will choose mbr or a boot partition and if there are more than one drive you will choose which drive.
The scripts that run during an update-grub, that you can run manually or will be run by Ubuntu when a kernel version is updated, include a script that looks for other operating systems to give you as boot options. This is the /etc/grub.d/30_os-prober and can be purged as described earlier or you can just set it to not be executable. This script only searches for other OSs and provides what it finds to grub.cfg it does not write anything to other drives or partitions.
I do think you should do some review of the Grub2 documentation and it will all make sense to you. https://help.ubuntu.com/community/Grub2
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