[Closed] Windows 8 - Driver_Power_State_Failure - how do I find out what is causing it?

HAd my Windows 8 machine for about 9 months now and it has been very good...over the last 2-3 months, it seems to restart itself daily and reports a Driver_Power_state_Failure error - but it doesn't say what is actually causing it.

Doing a nosey round the web gave me a hint that it could be some certificate things but everything installed on it is Windows 8 ready. I haven't installed anything new on the machine for about 5 months either so it isn't anything like new hardware/software causing the conflict.

I'm confused...anyone able to offer a more English-friendly explanation and suggestion of what I should be looking into?

Thanks.