HP Truevision HD driver digital certificate issue

Hi

My Pavilion G6 notebook won't recognise it's inbuilt webcam. I can see that the HP Truevision HD driver has the following error. "Windows cannot verify the digital signature for the drivers required for this device. A recent hardware or software change might have installed a file that is signed incorrectly or damaged, or that might be malicious software from an unknown source. (Code 52)".

When I try to update the driver, it tells me that it's already up to date. How do I fix the driver ? I am running Windows 8

Thanks