Leo runs fine if I boot with the disc in the drive, but naturally I don't always want that. I tried various standard approaches, but none seem to work.

I ticked 'MBR boot' during install as this is how it was set in 10.5.1.

Any ideas where else I can look to resolve this?

Anyone with thoughts on this?

There is probably a simple fix, but I'll be damned if I can find anything relevant on Insanely mac... even searching is a big huge P.I.T.A.

You need install the EFI bootloader for MBR.

This is what I'm referring to when I say:
I even have since tried installing on a freshly formatted partition, but it seems even worse... i cannot get to darwin now...

I've tried various standard tricks and have confirmed the partition is AF and * (active)... but still no boot...

Tried ensuring the disk name is all 1 word (this was a trick from Zephyroth's 10.5.1)... still no boot...

I'm running out of ideas here... any other ideas to help?