BitLocker Drive Preparation Tool Error

Hi,
Vista Ultimate (32 bit). Single partition 'C' drive.

I am trying to install BitLocker. I run the BitLocker Drive
Preparation Tool and receive the following error:

A problem occurred while preparing the drive for BitLocker Drive
Encryption.
Error: 0x80070005
Access is denied.

My basic understanding is that the tool should create an active
partition S: of size 1.5GB and move the boot files to the new active
drive S:.

Dell D820 with 30.2 GB free. Bios A09. TPM 1.2 chip is on and
activated.

I tried running as Administrator. I tried searching MS Knowledgebase.
I tried turning UAC off.

It seems like this should be easy.

Help?

-solon fox