This might not be good advice or what you wanted to hear but it is what I would do. The only time my computers have ever acted that way was when I have had tons of shareware and third party software installed. Meaning over a period of time installing a bunch of shareware apps on an older Mac. Anyway, here is what I would do.
1. First, run disk utilities, fix disk permissions.
If this does not work I would.
2. Go into the Library Folder and Backup the Mail Folder.
3. Then I would go into the User Account Library Folder and Backup the Mail Folder.
4. Then I would throw away the Mail Application and the files in the Library Mail folder and User Library Mail Folder.
5. Then I would take out the Operating System and install from the optional packages the mail application.
6. After it is installed, I would put both sets of files that I backed-up back into the proper library folders.
7. If that did not fix it, I would backup up all my important computer files, then zero out the hard drive and do a fresh install.
Just in-case you are not sure how to zero out the hard drive it is done through disk utilities under erase then click options and choose zero out.
To tell you the truth, knowing me, I would just do step seven to start with because I would know that mail should not be force quitting and would rather just have it restored to factory. You can try steps 1 through 6 and see what happens. Good luck.
MacsRules
