09-21-2011 09:38 PM
My X220 has BIOS 1.21 and a Windows 7 x64 installation with UEFI, and until recently, was using BitLocker drive encryption for two drives (mSATA SSD boot disk and 320gb magnetic data disk). A few days ago, I shrunk the 320gb partition to free up some space for the Windows 8 Developer Preview. I wanted to have this installed as a dual boot option with Windows 7.
I suspended BitLocker to do the Windows 8 installation. That install didn't go so well -- I tried starting the install from within Win 7 since I don't have dual layer media and can't seem to get a thumb drive to boot while in UEFI mode on the X220. Anyway, upon resuming BitLocker and then rebooting, I get prompted for the BitLocker recovery key, every time!
I tried all sorts of things: Decrypting both drives then re-encypting. Getting rid of the failed Windows 8 partition and expanding back D: to its original size. Manually clearing the Windows Setup entry (via bcdedit) that the Win 8 installer left behind. Clearing and re-initializing the TPM. Disabling the TPM in BIOS and then re-enabling. No go! Everything "seems" to work until I have the computer reboot while its drives are encrypted (while the key is not suspended), at which point I am always prompted for the recovery key.
I tried the option which verifies system integrity (through a reboot test) before beginning encryption. This results in the following error dialog which appears twice at the next startup:
Title: BitLocker Drive Encryption
Headline: BitLocker could not be enabled.
Message: The BitLocker encryption key cannot be obtained from the Trusted Platform Module (TPM). C: was not encrypted.
In the System event log, I see the following events logged for this problem from BitLocker-Driver:
Event ID 24636: Bootmgr failed to obtain the BitLocker volume master key from the TPM.
Event ID 24641: An unexpected error was encountered attempting to retrieve the BitLocker volume master key during restart.
If I tell BitLocker to do the system check before encrypting, then I get the above two errors plus a warning:
Event ID 24609: A key was not available from required sources during restart.
Has anyone got an idea of how I may restore my X220's TPM functionality? This is driving me nuts...
Solved! Go to Solution.