XCode can't resurrect !
This morning I was working but XCode decided it didn't wanted to so it crashed (again)
The stack trace was pretty explicit:
Process: Xcode  Path: /Developer/Applications/Xcode.app/Contents/MacOS/Xcode Identifier: com.apple.dt.Xcode Version: 4.0 (99) Build Info: IDEApplication-990000~36 Code Type: X86-64 (Native) Parent Process: launchd 
Date/Time: 2011-03-15 08:28:37.899 +0100
OS Version: Mac OS X 10.6.6 (10J567)
Report Version: 6
Interval Since Last Report: 296765 sec
Crashes Since Last Report: 46
Per-App Interval Since Last Report: 8739 sec
Per-App Crashes Since Last Report: 1
Anonymous UUID: CAF2FC67-76FB-483F-A019-9F18F7631207
Exception Type: EXC_BAD_INSTRUCTION (SIGILL)
Exception Codes: 0x0000000000000001, 0x0000000000000000
Crashed Thread: 13 Dispatch queue: Garbage Collection Work Queue
Application Specific Information:
fatal resurrection error for garbage block 0x200c3c880(AMDServiceConnection): over-retained during finalization, refcount = 1
objc: garbage collection is ON
Thread 0: Dispatch queue: com.apple.main-thread
0 libSystem.B.dylib 0x00007fff8574b2da mach_msg_trap + 10
1 libSystem.B.dylib 0x00007fff8574b94d mach_msg + 59
2 com.apple.CoreFoundation 0x00007fff82859932 __CFRunLoopRun + 1698
3 com.apple.CoreFoundation 0x00007fff82858dbf CFRunLoopRunSpecific + 575
4 com.apple.HIToolbox 0x00007fff838c893a RunCurrentEventLoopInMode + 333
5 com.apple.HIToolbox 0x00007fff838c873f ReceiveNextEventCommon + 310
6 com.apple.HIToolbox 0x00007fff838c85f8 BlockUntilNextEventMatchingListInMode + 59
7 com.apple.AppKit 0x00007fff8173be64 _DPSNextEvent + 718
8 com.apple.AppKit 0x00007fff8173b7a9 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 155
9 com.apple.AppKit 0x00007fff8170148b -[NSApplication run] + 395
10 com.apple.AppKit 0x00007fff816fa1a8 NSApplicationMain + 364
11 com.apple.dt.Xcode 0x0000000100000eec 0x100000000 + 3820
More stack trace ...
Thread 13 crashed with X86 Thread State (64-bit):
rax: 0x0000000000000000 rbx: 0x0000000200c3c880 rcx: 0x00007fff8574b2da rdx: 0x0000000000000000
rdi: 0x00000001227119f0 rsi: 0x0000000000000003 rbp: 0x0000000122711bf0 rsp: 0x0000000122711b20
r8: 0x0000000000001a0b r9: 0x0000000000000000 r10: 0x000000000000002c r11: 0x0000000000000206
r12: 0x00000001014dc000 r13: 0x0000000124d00010 r14: 0x0000000000000001 r15: 0x0000000000000002
rip: 0x00007fff874ffd5a rfl: 0x0000000000010202 cr2: 0x00000001013853c0
0x100000000 - 0x100000fff com.apple.dt.Xcode 4.0 (99) <1AEE2FF2-CB04-3CDF-B085-C683453BEFD7> /Developer/Applications/Xcode.app/Contents/MacOS/Xcode
More drivers ...
Model: MacBookPro5,2, BootROM MBP52.008E.B05, 2 processors, Intel Core 2 Duo, 2.8 GHz, 4 GB, SMC 1.42f4
More specs ...
XCode can do a lot of things but apparently not resurrect dead objects !
Surprising fact: I almost rarely experiencec crash on my mac except for IDE's
Apple tends to experiment with Xcode itself more than they do with their other apps. Dogfooding and all that. For instance Xcode became 64-bit and garbage collected back for 10.5, while most Apple apps became 64-bit only for 10.6, and I'm not sure they rewrote many apps to be garbage collected even afterwards, it's more meant for new developments. As a result, I have indeed seen more instability from Xcode than from other Apple applications.
Try pressing continue!