I already had Clover R1000 installed when I found this was a problem for me. I modified the config.plist file on the EFI partition only by adding the keys noted below with the following procedure: 1. Open a terminal screen 2. mkdir /volumes/efi 3. sudo mount -t msdos /dev/disk0s1 /volumes/efi (use whatever hard disk name is appropriate for you) 4. nano -w /volumes/efi/config.plist 5. Paste in the following. Change the serial number <key>RtVariables</key> <dict> <key>MLB</key> <string>W88GG136DHJQ13579</string> </dict> <key>SMBIOS</key> <dict> <key>SerialNumber</key> <string>W88GG136DHJQ13579</string> </dict> 6. Modify the serial number "W88...." to match yours, and add five random digits. I added 13579 to my existing serial number. I got my serial from "About this Mac" > "More info..." Don't know if the original serial number is important or not and I didn't care to find out. 7. Save file. 8. Rebooted and logged in successfully.