Latitude D820 The speed of processor 0 in group 0 is being limited by system firmware

I am having problems with my laptop going into sleep mode and being unable to wake it up, therefore having to shut it down and restart. It may go for a day or two without doing this, but then it happens again. I have the latest BIOS update (A10), but am receiving the subject error message in the event log for both processor 0 and processor 1. Not sure if it's related, but certainly seems critical.

There are also a lot of stopping starting messages like these: The Multimedia Class Scheduler service entered the stopped state. And then there's this:

The dldtCATSCustConnectService service failed to start due to the following error:
The service did not respond to the start or control request in a timely fashion.

Any suggestions would be greatly appreciated.

Cathy