Xcode 4.6.2 app crashes on every second run
Found another way to fix this without moving the debugger to GDB. I usually just re-run an app by pressing ⌘-R while the app is running. Instead, kill the app from Xcode with ⌘-., wait 5 seconds and hit ⌘-R to run it. Counting the 5 seconds by saying "I love Xcode" seems to help too.
Edit: This issue is fixed in 4.6.3