How to fix this project in order to pause at breakpoints in Xcode4?

I am trying to run this Xcode project sample : http://developer.apple.com/library/mac/#samplecode/HID_Explorer/Introduction/Intro.html

My OS version is 10.6.7 so, I changed the "Base SDK" parameter in the "Build Settings" panel from "10.5" to "Latest Mac OS X (10.6)".

If I press Cmd+R the application runs correctly. However I set a breakpoint in the code and try to run the application again, the application becomes inaccessible (the mouse cursor becomes a rotating colored circle when hovering over it), but no breakpoint seems to be hit in Xcode.

By the way this message appears in the debug window when I try to run the application :

warning: This configuration supports "Darwin64" but is attempting to load
an executable of type i386 which is unlikely to work.
Attempting to continue.
&"warning: posix_spawn failed, trying execvp, error: 86\n"
[Switching to process 9602 thread 0x0]
warning: This configuration supports "Darwin" but is attempting to load
an executable of type i386:x86-64 which is unlikely to work.
Attempting to continue.
`/usr/lib/dyld' has changed; re-reading symbols.
warning: Inconsistent DBX_SYMBOL_SIZE

Pending breakpoint 1 - ""main.c":503" resolve开发者_如何学JAVAd

I use Xcode4 and I suspect changing an other project setting should fix my problem, but I cannot figure out which one. Which setting do I have to change ?

I think I found how to fix my problem. I also changed the "Architectures" setting in "Build settings" from "Standard (32/64 bit-Intel)" to "32-bit Intel" and it works now. Actually some Carbon functions seem not to be available to 64-bit application : http://developer.apple.com/library/mac/#documentation/Carbon/Conceptual/Carbon64BitGuide/HIToolboxChanges/HIToolboxChanges.html

I think it is a race condition, pausing one of the threads... I am carbon stupid.