Connie,
Thanks for the clarification but I just finished fixing the W98 machine. Yes, W98 only works with the "old" settings of 127.0.0.1 and the # format in the POP and SMTP addresses.
As I said, XP works ok with the 4.5, but Thunderbird only works the old way. I have to update TB to the new .9 and see what happens.
Right now, all my email is working on my 3 machines.
What a nightmare for 2 days!
Still don't know if any fix is in the works.
Oh well. It makes life interesting.