I was able to find the fix. Based on a recommendation from a friend who edits professionally, I toggled the RT Pop uP Menu on the timeline (upper right corner) from Safe RT to unlimited RT back to Safe RT and the timeline started acting as it always did. No yellow, everything was either red or green (render status) and I was able to change the canvas background back to black and still see the clips. Don’t ask me why, but it worked.
Thanks Abby!
MAC PRO Leopard OSX 10.5 – 2.8 Eight Core (2x Quad Core), 10GB Mem, 3.20TB HDD, ATI 3870