Security

I have a Windows 7 Optiplex 580 that has bitlocker enabled. When I restart the system its fine. If I shutdown the system and then use Wake On LAN to start it, its fine.

However, if I shutdown the system and then use the power button to start it back up, it triggers recovery, and I can see in the windows event log that a TPM PCR registry mismatch had occured.

If I disabled and then enable bitlocker (to make it reset the PCR), the system is fine until the next time I use the power button.

What could possibly be going on here?