Currently Being ModeratedNov 14, 2013 4:24 AM (in response to Peter Best1)
Have you called AppleCare, using your free 90-day support? They maybe best placed to help solve the problem and you should not be having to troubleshoot anything. That said, it is possible that there may be some incompatible software causing the problems.
When the machine shuts down is it a kernel panic - screen goes dark and you are presented with a multi-language box telling you to restart. If so, post the panic log on here and someone may have some ideas:
You could also run the free EtreCheck and post the contents of its report on here. I'm not an expert at spotting possible causes of problems, but there are plenty here who are:
Separately, although I haven't followed the info closely, there have been many reports about problems with WD drives and Mavericks. A bit of searching on here and Google may throw up more info.