In case you tried to email me between June and October 2009

. . .  apparently Yahoo Mail "Plus" (that I pay for) has been inexplicably defaulting my "from" field to the wrong email address 50% of the time since June. 

Maybe the "plus" refers to "we'll make the "reply-to" from the email address you set as default, "PLUS" we'll sometimes make it to a totally different email address just to mix it up and make life more exciting".  The result is that I now have a lot of replies to various emails sitting in a very old email account that I no longer look at that I was completely unaware of.  No settings were changed, and half the time it works correctly so I'm baffled as to why this happens.  I think I'm going to switch providers.

If you REPLIED to any of my emails in that period of time and expected a reply from me that never came, then my apologies.