(1) First of all, use your Mac's System Preferences... > Accounts to delete Photo Booth from your Login Items.
After you restart, you can test Photo Booth to see if it works. I doubt that this change will make Photo Booth work properly in your normal user account, but it will stop Photo Booth from launching automatically at startup or login.
(2) Although this will not likely correct the problem with your user account either, your posted system shows that you are using Mac OS X (10.6.5). If this is correct, unless you have compelling reason for now doing so, you should update to the current version of Snow Leopard. Here is the method I suggest:
• Unless you have a current backup, make one now.
• Use your Mac's Disk Utility to repair permissions.
Then download and apply the latest Combo Update.
The current Combo for Snow Leopard is here:
http://support.apple.com/kb/DL1399
• Repair permissions again immediately following the system restart
that completes the Combo update.
Properly applying the Combo version of updates can sometimes correct software problems.
(3) Now to your specific problem. You have already done some very good troubleshooting. Your testing seems to show that your normal user account has somehow been damaged.
Because there are many thousands of files in any OS X system, I have never successfully "repaired" a user account. It is faster, easier, and more reliable for me to merely change to a new account that works properly. Here is how I do it.
First, if you do not already have one, make a current backup of your important files. If you need help, see: http://support.apple.com/kb/HT1553
Next, decide whether you want to use one of the existing test user accounts that you already know works. Renaming account names can cause serious problems, so, if you want a different name for your new everyday user account, it is important to create the account with the name you like. Test the new account, too, to be sure it is working properly before proceeding.
Now, copy needed data from your backup into your new user account that works. Begin using this new account as your every-day "main" login account. Do not move or delete anything from the old (damaged) account at this time.
If you must add any third-party items to your new account, add only one at a time. Test thoroughly before adding another third-party item. This technique will help you quickly identify any particular item that might have been the cause of a conflict in your old account.
Use your new account long enough so you can be certain that everything you do with your Mac is working properly in the new account. Depending on how you use your Mac, this can take weeks or even months.
When you are certain that all is well with the new account that is now your normal account, you can throw away your damaged (old) original user account folder to reclaim its disk space.
(4) If you want to try consider some other possibilities on your own, this article might help you find the root cause of your trouble so you can determine what must be fixed.
Message was edited by: EZ Jim
Mac OSX 10.7.3