first, the "-x" boot flag is for safe mode. when you replaced the kexts did you repair permissions. this is a common error. To fix it, boot into single user mode using the forced Extensions load:
and this will give you a console-type boot.
first mount your hard drive:
then change to the Extensions folder:
Code:
cd /System/Library/Extensions/
next, repair permissions of the folder:
Code:
chmod -R 755 * && chown -R root:wheel *
I follow this up by removing the Extensions.mkext file so the system will load all the Extensions at next boot and re-cache them into a new .mkext file.
Code:
cd ..
rm -Rf Extensions.mkext
finally reboot:
I think you are getting a hang at the mDNSresponder error because of this permissions problem because you altered the IOFamilynetwork kext file. when you boot in safe mode (-x) you bypass this because it isn't a needed function of the OS in order to boot.
Hope this helps explain things a bit. If this isn't the problem, we'll dig a little deeper next time.