Here is what I did to try and fix the problem:
I deleted the Preferences List (.plist file) from cris\library\mail and from \library\mail.
I forced Mail to rebuild its index by deleting the ~\library\mail\Envelope Index file.
I tested my computer's memory by running MemTest from http://www.memtestosx.org/.
I Verified Disk Permissions, I Verified Disk by using Disk Utility.
Everything checks out ok and yet Mail still crashes - bummer.
That's as far as I'm going tonight thought. I will deal with it tomorrow when I am back in Redmond.