I have an HP laptop with a TPM 1.2 level chip. I have successfully encrypted the C: drive with bitlocker. The OS is 64-bit Windows 7 Ultimate. But I had the same issue when I had it formatted as 32-bit. Every time I boot it, I have to enter the key. I have found several articles about this and they all pretty much say the same thing. I have decrypted the disk, reset and reinitialized the TPM module and reencrypted the disk and I get the same thing. Here is the message that I get when I start: The system boot information has changed since bitlocker was enabled. You must supply a bitlocker recovery key to stsart this system. Confirm that the changes to the system boot information are authorized. If the changes to the system boot information are trusted, then suspend and resume bitlocker. THis will reset bitlocker to use the new boot information. Otherwise restore the system boot information. I believe that I have done this before, but to check it I did the suspend and resume and when I rebooted it came up OK. But then I just shut it down from within Windows and when I started it up again I was once again asked to put in the key. I've seen a post that mentions some vulnerability, but since this is a new install and I have had the problem right from the start, I doubt if some hacker has managed to get past our company security just when I am setting this up. I have done bitlocker on other machines without issue, but can not figure out what is going on with this one. I am about to abandon this and go to truecrypt.

Figured it out. Problem was specific to my model of HP laptop. Answer is here: http://h30434.www3.hp.com/t5/Other-Notebook-PC-questions/HP-Probook-6540b-with-Window-7-Bitlocker-Major-Issue/td-p/266926/page/2 Had to uncheck PCR 0

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