Comment 2 for bug 287853

Frankly, I think this needs to be resolved in kgrubeditor. The grub framework we have is one that we're pretty much stuck with until we can switch to grub2; if kgrubeditor can't edit menu.lst without generating conflict errors, then it ought not to give users the option.

In your case, I think what you really want is to remove the packages for the obsolete kernels you're no longer using, rather than editing menu.lst by hand.