This is pretty much guessing, but I did experience the same problem.
It might be coincidence, but for me this problem appeared the first time after I updates OS X to 10.8.4. Since then every other Run ends in a crash.
The backtrace for my case looks like this:
(lldb) bt
* thread #1: tid = 0x1c03, 0x9573da6a libsystem_kernel.dylib`__pthread_kill + 10, stop reason = signal SIGABRT
frame #0: 0x9573da6a libsystem_kernel.dylib`__pthread_kill + 10
frame #1: 0x9476ab2f libsystem_c.dylib`pthread_kill + 101
frame #2: 0x024e857b libsystem_sim_c.dylib`abort + 140
frame #3: 0x026afb4e GraphicsServices`GSRegisterPurpleNamedPort + 348
frame #4: 0x026af69f GraphicsServices`_GSEventInitialize + 123
frame #5: 0x026afc1f GraphicsServices`GSEventInitialize + 36
frame #6: 0x0076ed99 UIKit`UIApplicationMain + 600
frame #7: 0x0000225d XXX 3`main(argc=1, argv=0xbffff36c) + 141 at main.m:16
frame #8: 0x00002185 XXX 3`start + 53
Since it works perfectly fine 50% of all launches, and it worked the months before I did the update, and it works with gdb, I'm pretty sure this is a bug on Apples side.
A workaround for this problem might be to switch from lldb to gdb. It worked for me.
You do this in the scheme editor (press command + <). Change the debugger to gdb in the Run scheme.
Since this is like the third question (others were closed already) or so that I saw on stackoverflow in the few days since 10.8.4 was released I'm pretty sure this behaviour is related to the update.
