Hi all, David,
I own Macbook 6,1 and how I fixed the issue.
Download Firmware Update 1.7 http://support.apple.com/downloads/MacBook_Pro_EFI_Firmware_Update_1_7_
MacBookPro5,5 the same hardware MacBook6,1, to extract MBP55_00AC_03B_LOCKED.scap.
mv MBP55_00AC_03B_LOCKED.scap MB61_00C8_B00_LOCKED.scap
sudo bless -mount / -firmware MB61_00C8_B00_LOCKED.scap --verbose
Shutdown and restart Mac update the firmware and restart automatically.
Attention consequences, the MacBook6,1 as new model identifier MacBookPro5,5 but works well, possible problems could rise with future firmware update.
Thanks for all, The Power of Community.