I don't think it's app related. I had reflashed the stock firmware and used the reset instructions listed in this thread and without installing...
Has anyone exchanged their Captivate because of the random turn off issues? If so did this fix it?
I can live with spotty GPS and getting locked...
I think it defaults to 1280x720 (max). There are also options for 720x480, etc.
You can use root explorer to find them under system/media/audio/ringtones.
I uploaded the Samsung_tune.ogg file for you.