....could it be a sneaky, back-door, firmware-type update that was smuggled onto our systems with and OS update or a "Security Update?"
that is what I think, because
after trying about a dozen different fixes listed on the internet, I reinstalled on a separate partition my OS 10.4.10 computer disks that originally came with my 2.0ghz iMac, not allowing it to do any updates....
Bingo, all disk burning works again.
What is this, Apple?