IMac won't wake after sleep

Question

Hi
I have a brand new iMac 21.5" with Hybrid drive.
Its OS and apps are fully update to date.
Strange thing is that it won't wake from sleep.
To reboot, I have to turn the power off at the wall and back on again. Neither of the usual
wake/reboot processes work (holding the power button briefly or holding the power button for
> 10 seconds). No combination of opt/ctrl/cmd/power work either. I have to turn it off at the wall
and back on again, after which it immediately boots.
I've reset the SMC and NVRAM/PRAM.
I've checked the power options - which are set to defaults (sleep after 15 IIRC).
I've also checked the console log at the time of sleep - and there is no indication of anything
going wrong (an example is below).
Does anyone have any other ideas as to what I can try before going through the painful process
of sending it into the shop?
Many thanks.
Paul.
Console log below. You can see the machine went to sleep after 12:05pm, and I woke it up and 8:20pm. There seem to be no unusual messages in the middle.
(The SASL failure is email... still working on that).
29/04/15 12:05:33.391 pm identityservicesd[265]: <IMMacNotificationCenterManager: 0x7fde94947690>:   DND Enabled: YES
29/04/15 12:05:33.392 pm identityservicesd[265]: <IMMacNotificationCenterManager: 0x7fde94947690>: Updating enabled: NO   (Topics: (
29/04/15 12:05:36.577 pm Mail[241]: Failed to start the SASL connection
SASL(-1): generic failure: XOAUTH2 requires user
29/04/15 12:05:44.142 pm Mail[241]: Failed to start the SASL connection
SASL(-1): generic failure: XOAUTH2 requires user
29/04/15 8:20:11.406 pm distnoted[232]: # distnote server agent  absolute time: 6.328668630   civil time: Wed Apr 29 20:20:11 2015   pid: 232 uid: 506  root: no
29/04/15 8:20:11.592 pm otherbsd[231]: Could not get containing identifier from bundle: CFBundle 0x7fa663c16190 </Applications/Utilities/HP Utility> (not loaded)
29/04/15 8:20:11.592 pm otherbsd[231]: Could not obtain containing identifier for LoginItem. This LoginItem will not be bootstrapped: LoginItems/HP%20Device%20Monitor.app/ -- file:///Applications/Utilities/HP%20Utility/Contents/Library/LoginItems/HP%20De vice%20Monitor.app/Contents/Library/

Answer 1

I have gone to the apple support team - and they took me to the standard apple "what happens if your mac won't turn on" page
(If your Mac won't turn on - Apple Support) and walked me through the standard checks (which I'd already done).
The support guy thought it was a bad driver - I'm not so sure as I haven't installed anything new (just updates).
Anyway - I was just hoping/wondering someone in the wider community had seen this issue before I take the machine
in for servicing.