naquaada, I believe the XCode crashing issue is related to 10.5.2+, because at 10.5.1 this didn't happen to me either.

However, when I installed XCode on my 10.5.2 system, the system crashed almost at the end of the install.
I rebooted and had to fix the CHUD kernel error. After that XCode worked fine, even though it didn't seem to have finished the installation, which it apparently did.