So I'm a friggin' idiot. The problem was my CD-ROM drive all along. Apparently the external drive that works just fine with my Octane2 isn't 100% happy with my Indigo2. I discovered this by trying out my Onyx2's drive, which is now happily installing 6.5.22 on my Indigo2.
So now I have about 17 working burns of Disk 1 of 6.5.22 - anyone want one?
So now I have about 17 working burns of Disk 1 of 6.5.22 - anyone want one?





