I was bashing my head against the wall with this one too, but it wasn't the end of the world so I didn't worry about it.
Then my power bill came and it was 180% the usual cost. WooHoo! (also turned out my fiancee had plugged in the 1970's fridge in the basement).
I followed Lexone's guide and ran into the sleep wall.
Anyways, here is the fix that I found:
First of all make sure your running the BIOS supported by your DSDT (I recommend using the TonyMac dsdt myself since all the other repositories are going to be based in what's most popular).
In BIOS set the C-state limit to C1 (google for further details). This will fix audio issues without needing to install Nullpowermanagement.kext.
Next: Install intelpowermanagement.kext from the latest multibeast and remove nullpowermanagement.kext
Now remove the usb 3.0 kext. If your machine is sleeping once, then locking up on the second attempt this is the culprit. Should be PXHCD.kext... remove it.
Finally install pleasesleep and activate it.
Enjoy! Worked for me! Geekbench improved plus sleep plus audio! No usb 3.0 but I can live with slightly slower transfer rates.