It is worse than I thought, at least with TB2.0pre. As I usually do, I download the zip nightly, and then unzipped it. I found out that it is not the update which makes itself default, but the unzipped program. I have unchecked the default for Mail, and found out that it became grayed out and still checked. If I select mail from Firefox, I could not bring up TB 1.5.0.10, which had been my default all along. Finally, with both mail applications closed, I could not delete the 2.0pre. I was being told that it was being used by someone else.
I did a virus scan, and, of course I found nothing other that TB2.0 has 1590 files. Wow!
For now, I have to hang on that unwanted program. Will try to reboot later, or see if there is any extention which causes the problem.
As for 1.5.0.10, I, grudgingly, decided to make it default, for now. 1.5.0.10 was installed in the default location, i.e. Program Files|Mozilla Firefox. I, still don't understand this behavior.
I closed Firefox, and, I was able to delete TB2.0pre. Why? I have no idea, but good riddance.
At mozillazine.org it was suggested that all of the above is due to a regression which appeared when the programs were made compatible with Vista. We will see.
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.10) Gecko/20070216 Firefox/1.5.0.10
