Resolved these problems. I had connected the component out/in-puts straight away. The new sd-3990 must be set to component in the setup menu by using the the video in/ou cables included with the player. (This was not very clear in the instructions.)
Toshiba is sending me a upgrade disc that should take care of the problem with the old sd-6200. They were almost certain that the chips need only to be updated.
If the 6200 worked until yesterday I doubt that a software update is going to help. The software updates usually help read discs with new features that are released from time-to-time or those on newer high-speed media.
Note that I also had this problem intermitently with my XS32, except it knew enough to stop trying to read a disc after 30 seconds or so.
Usually this means a dead or malfunctioning laser or it could be the processor that controls all activity in the player. The older processors weren't very effiecient and got very hot, and Heat is #1 enemy to electronics.