After upgrading from Ubuntu 12.04 LTS to 14.04 LTS, I began to see an error during startup:
error: Diskfilter writes are not supported. press any key to continue...
I tried applying the patch suggested at https://askubuntu.com/a/498281/154956 but ended up with an unusable system (I may have done it incorrectly).
I have my BIOS set to ENHANCED SATA mode.