After 12 hours, finally...
For everyone going bonkerz over this:
Here is the cause, and the solution:
With web-type emails like Hotmail, Yahoo, Gmail, AOL, Lycos, maildotcom, etc, we are not supposed to be able to use these desktop mail clients, like Thunderbird, by design. They want us to directly sign in so that we will increase traffic on their servers, so that they can sell more advertising. What people don't realize is that WE are the products. Hotmail, etc, SELLS US to the advertisers, and we all know what that brings us...
Mozdev's WebMail addon/extension for Thunderbird. I have the version labeled for Thunderbird 2, but it seems to work just fine with my Thunderbird 3. I have Kubuntu Linux but as far as I know it is cross-platform, use it on Apple and [shudders] windoez, too.
Here is a simple YouTube tutorial:
Here is where to get specifically WebMail:
Here is Mozdev's main site:
Here is another Linux resource regarding this:
HEED THE INSTRUCTIONS!!!
Install the basic WebMail module FIRST.
Then, install the module specific to you webmail, install as many as you need.
Install another module (if needed).
I have Hotmail, Yahoo, and AOL all running just fine. I could not get these accounts to operate any other way. My ISP-based email worked fine from the start. I hope this fixes your problems like it did for me, and dissipates the stress.
Credits, and props go to Eric.
EricTRA, once again, brother, thank you! There's another beer comming your way!