In order to resolve this problem I have resorted to setting my system to NEVER sleep (which Apple recommends not be done) and what I find extremely strange is that when I put my system to sleep by clicking on the Apple symbol located at the top left of the screen and then select SLEEP the unit will wake even after sitting overnight. However, when the Energy Saving setting in System Preference is set to the default position and the system is left for an extended period it will not wake from sleep. I find this extremely strange and ergo I am wondering whether there is any connection between both settings/action.
Consequently I am using this medium to ascertain whether any other member has experienced the same problem and if so has anyone discovered the cause and what is required in order to resolve this extremely annoying problem. All comments/suggestions etc. will be greatly appreciated.