quit unexpectedly

Greetings:

Mail, Safari, help, SuperDuper all quit within seconds of launching. other apps quit at random times. I put plists in trash and set up a temp. user. With temp user, Mail wants me to set up a new account which I didn't do because I remember how hard it was to get mail to work and don't want to create more problems. the set up screens do not quit until I cancel. I tried changing the permissions but it still wanted me to set up a new user account. Safari works fine with the temp. user. Firefox works fine with both users. I subscribe to mobileme. I have every software update available. I haven't added new software although I did install spyder 3 express a couple of months ago. I'm wondering, too, if I should drag the plists out of the trash and put them back where they were. I have had several kernel panics during the past year but no other problems. when apps began shutting down, I tried restart and shut down and safe boot, too. Now, I realize that safe boot does not actually repair disk so guess I should do it again and run repairs?

Thanks for any help.