Cannot find TPM Device

I decided to build my own PC and followed the example of the one featured in Custom PC magazine.

Asus P7H55-M Motherboard Intel G6950 processor and 4Gb RAM. Fitted an arctic fan as intended to overclock it.

All went together well and installed Windows 7 Professional.

Changed the BIOS settings for an overclock to 3.5Ghz as shown in the mag. Checked fan and CPU all running ok. Occasionally at startup I get the error message

Overclocking failed
Press F2 to load defaults
Cannot detect TPM device.

Have searched on the internet and checked the Asus web page for support, which has a mandatory field for serial number of motherboard. Phoned them and got an automated message telling me to check their website.

Google is not my friend - leads me down many paths with no answers.

Oh and have installed the latest BIOS drivers

Any help would be appreciated
TPM - Trusted Platform Module - very loosely a sort of smartcard thingy identifying your computer and providing security services to applications that mostly don't exist yet - you shouldn't need it unless you are planning to use Bitlocker?
message only appears when computer is overclocked. Should I disable bitlocker in startup ?
Aha just thought, splash screen comes up so fast normally, that I don't see it. Only see it when overclocking fails and TPM device not detected is the second message, which means that it would only halt on the overclocking error.

Problem now is why can't I overclock it ?
Dunno about the overclocking but there is a strong history, if you check the M$ forums, of TPM not being recognised on W7 - normally because an incompatible driver has been picked up from somewhere online. As we seem to be agreeing - who cares!

I'd wait for a speed expert rather than a security one to come along ...