If a unbootable partitio is marked dos, it is added to
lilo.conf automaticly. Lilo will not install, and you do
not get a meaningfull error message. In fact, the lilo
error message isn't even printed to the other VC's. Idealy,
the installer should at least parse the error enough to
tell you which partition is affected, or at least press
<ALT><F3> for more info. Oh, and have it so you DONT have
to run lilo manualy to figure out the problem.
Issue is resolved in 6.1 release.