First, Thanks John T. Haller for the great work!
1-) I was doing an automatic update to my Thunderbird when the computer unexpected shutdown.
2-) After that, I was unable to run Thunderbird again.
3-) So, I decide to download and install a new version of portable Thunderbird (I copied the profile from the old installed version to the new one).
4-) Now it runs fine, but I can not get my emails, I am getting the error:
"This folder is being processed, ....."
or, instead I got this message in the status bar: "Downloading message 1 of 18" and nothing is downloaded.
I did a search in the Mozilla forums without success (applying the suggestions found there).
I downloaded all the versions (Thunderbird alone, Thunderbird with Enigmail), older versions of Thunderbird, etc. Copy the profile to this installations and the same happens. This suggest that the problem is in the profile.