AMD released its Crimson ReLive drivers last week but modders discovered AMD re-enabled BIOS signature enforcement with the launch of ReLive. What this means is that the ReLive drivers will refuse to load if they discover your card has a BIOS with a hash value that differs from the factory value.
Basically, if you modded your card's BIOS in search of higher overclocking, more voltage or customized fan settings, the hash in your BIOS is no longer recognized by AMD the driver, since it differs from the factory values.
On detecting such a modded BIOS with an invalid checksum, the Crimson ReLive driver won't load, meaning that the system will run with the VGA fallback driver only, without 3D acceleration and Radeon Settings will not start. However, you can force your modded BIOS to load on Crimson ReLive if you're willing to jump through some hoops.
Fortunately, there's a workaround that will get you back in business. TechPowerup describes the steps at their website. This hack is also required if you want to mod the RX 460 to unlock more stream processors (more about that in the next post).