I don't want to uninstall IE8 because I like it. All my computers are running it now so I can't check to verify if that is the problem.
The Yahoo sync (whether IMAP or not I don't know) is okay now. It was saving a copy of the messages I sent from the Blackberry on Yahoo on the web even when I selected "delete from handheld and from mailbox." Unfortunately I was testing this using my own accounts. Meaning, sending a message from my Yahoo account (using BB) to my Gmail account. It must have known it was "me." When I send a message to somebody else it does work (it does save a copy of the sent message but I also get a copy in Outlook... then I delete from Outlook and in turn it deletes from the BB.) I am able to manage everything now from Yahoo through Outook or Yahoo on the Blackberry.
So, just in case somebody is having the same trouble - test only using "other" people not your own accounts (which might be listed under your own contact info.)