I have been ussing mozzilla-thunderbird 1.5 for a while without any
But today, when I tried to send a message, the program began to crash
as soon as I clicked the Attach icon. I tried this several times. I
turn off the computer. I did reinstall the software and I even migrated
to the latest version of the program with the same results.

There is something to do besides reinstall the whole operating system?