everytime i try to use mail, mail becomes totaly unresponsive. what should i do?

I have a friend who experienced this same issue. He, just like me, did an upgrade install. However, my Mail works fine. (It went through an "upgrade" process to update my messages to the latest version of the program). Try backing up and then deleting /Library/Mail (in your user account) and see if that makes a difference. You won't have your old mail available anymore, but at least it will be backed up if you ever decide to go back to Tiger and Mail should not freeze anymore with the new mail it creates.

that worked, thanks!