You are not the only one. I will be playing music in my car and all of a sudden the music cuts out, for me to discover the screen black for a good 20 seconds before the thinking wheel comes up then asks me for my code to get back in.
Plus I have the issue where it is corrupting my back-ups I do. It makes me want to cry it really does...
I've just spend 4 hours downloading the restore from Factory settings using iTunes, setting up the phone as a new phone, now I'm restoring my latest back-up and crossing my fingers all is good. It will probably take a good 2 weeks to see if this has solved anything at all
This is what I got from @AppleSupport on Twitter.
We'd like to make sure you have a current back up of your phone. That way, we know your info will be safe as we troubleshoot with you. Here's how: http://apple.co/1QbHq1x
After the backup is complete, we'll restore the phone back to factory setting using iTunes on a computer. This will erase all the data on the phone, but you'll be able to move it back to your phone from your backup.
Initially, we'd like to have you set the phone up as new, rather than from a backup; so we can test the issue you've been experiencing.
Here are the steps for restoring: http://apple.co/1L6v9g4 Let us know if you have any questions throughout the process.