Yesterday I updated the Xcode to the new 4.5.2 release, because, as described in the release notes, the new update solves a lot of annoying problems:
Fixed Xcode app and LLDB debugger crashes reported on Xcode 4.5. 12482521, 12482518, 12481393, 12481829, 12481363, 12481302, 12481396, 12482364, 12514294, 12364375, 12481322, 12481370, 12481398, 12481373, 12489094, 12483605, 12481863, 12482083, 12482540, 12481426, 12482542, 12481390, 12482362, 12481885
Editing User Interfaces
Improved stability when editing storyboards and using Auto Layout. 12482514, 12482536, 12482526, 12482548
Fixed an LLDB memory leak. 12483722
Improved behavior when quitting iOS Simulator directly. 12481405
Fixed occasional Xcode hang when submitting an app to the iOS App Store. 12482847
After about an hour of download and installation I was ready to come back to my work
But I had an unpleasant surprise
The Xcode said me that it wasn't able to connect to process ID 0
I tried switching from lldb to gdb
then I tried to disable gdb
last I found the solution, in the iPhone simulator application I reset the configuration.
I had to do this for each version of the firmware.