What can I say...
I ran disk warrior, mainMenu, replaced the mail and mail downloads folders with backups, replaced the prefs file, used pacifist to reinstall Mail (didn't help), reinstalled the OS (archive and install) but things just got worse; mail newer than 2005 totally disappeared, on a fresh install mind you, and all of this because my computer didn't start up after the last security update...
Then I decided to do a clean install and spend 10 hours reinstalling/updating other software (of which 5 hours on installing/updating the damned Adobe CS2 suite, enter your admin password every minute, the updater stalling every five minutes, what a drag)
Which brings me to the point: why doesn't apple make it easier to reinstall native apps like mail, addressbook etc because every time I was forced to reinstall the OS, it was one of these apps not working. Seems kinda stupid and M$ like to force users to reinstall the whole system if just one app is not working. But maybe that's just me complaining....