My Shuttle SD30G2 Hackintosh has been upgraded to Mac OS X 10.5.5. The upgrade was performed using the 316MB, Mac OS X 10.5.5 Update (not the Combo Update), following the steps below:

Open Terminal 

sudo -s 

*type password* 

while sleep 1; do rm -rf /System/Library/Extensions/AppleIntelCPUPowerManagement.kext; done

Open 10.5.5 Update Installer 

Run update BUT DO NOT RESTART 

Go back to your Terminal and press Control C to end the script 

Restart and boot with -v

The Hackintosh was restarted with everything working except Audio. Fixed the audio and now the Shuttle SD30G2 is running Mac OS X 10.5.5 without any problems. The Shuttle SD30G2, a hackintosh owner dream machine.