I have installed the PPC edition of Ubuntu - Warty Warthog edition, onto my G3 400 iMac, it was working fine and then I ran "base-config" as root (well, sudo) and installed all the packages available on the install disk (which I downloaded from ubuntu, and wrote the iso to cd-rw on my dad's windows box, using Nero Express.

The partitions were 40GB to linux filesystem, 512MB to swap, and 1MB to boot.

There seems to be a problem with yaboot which is installed on the 1MB of bootspace. When I try and boot ubuntu, it gets through stage one (select CD boot or GNU/Linux) and then it gets to yaboot, which asks me to select Linux or old, whichever one I select I get the mac Open Firmware screen (bright white) and that asks me to "Release keys to continue" after reporting a default catch (I forget the code)...

If I try and boot from a CD at the first boot strap, it simply returns to the first bootstrap after hesitation and apparent "Booting CD", I have tried this with the Fedora Core 4 (test), Mac OS X Panther, and Ubuntu boot disks.

Any help would be awesome. -radical edward

I had this problem with my iMAC but it was with a new release of MacOS. The firmware was out of date and needed to be updated. In my case the O/S, 9.2, had the firmware on the CD. For the iMac though you need to open the access panel and insert a probe into the correct hole so that it will accept the firmware update from the CD. This prevents you from breaking you machine if you accidently click the application on the CD, etc. I'm supposing this is the problem since you state it happens with the OSes you stated in your comments.

You can try Apple's "Info Alley" for the howto or the Apple MacOS CD, but the firmware updates are only on the MacOS CD' unless they changed their policy recently and I don't know about it.

EDIT: This screen comes up when you try to install certain newer versions of MacOS. There was a document at Apple's support site and in the "Info Alley" newsletter that iMac's needed a firmware update to install the 9.0 > 10.0 MacOS releases. I'm guessing you tried to install MacOS X and that's when this all started.