I also have a DH77DF board and a Crucial m4 msata 1280GB SSD. They are working ok together, actually the only problem that i have is that the BIOS do not boot from the ssd automatically, i always have to press F10 in boot and then select the drive to boot from it. The strange thing is that when i first installed the ssd the motherboard booted from it automatically, but one day after i swapped some disks i could never again boot from it. As i also have this problem in another intel board (DH61DL) with a old hard disk i am used to it...
I never had to set anything in the bios to make it work, nevertheless, i think you could try the following things:
- Try the F10 option during boot;
- Set the msata to hotplug in bios;
- Update the BIOS to the latest version;
- If you can install the SSD in another machine and update it's firmware to the latest version ( Crucial releases new SSD firmware | Hardware.Info United Kingdom).
As for the screw (this board has only one screw hole) IMHO it is just as Victor_intel said.
Well, good luck.
PS: Sorry for my "engrish", it is not my native language.