To 100% rule out the most obvious - USB in
SELECTIVE suspend - because you have REGULAR ALMOST TO THE MINUTE hourly errors
Thats power settings/bios setting related
So, you have to:
Just unplug anything connected to your PC that is USB (or any
wireless module for like a mouse or keyboard)
That includes printers, hubs, mouse, KB, eSATA enclosures, flashdrives, cardreaders etc
Everything
Something (prob external enclosure or hub) is doing its green thing to save power. When you have a stack of USB devices connected if only one is not compliant, it wrecks all the others. And thats why you should also always enable legacy USB option in bios if there, besides 2.0 (or 3.0)
So once you get a bare system and it works error-free, you can start adding back in one device at a time.
Note that your drives (since you have now determined they are not bad) not waking up in time or when needed, is the end result error
symptom , not the cause.
An oddball screensaver can also affect turn on, wake up from suspend
Shut that down also.
Until you do the above, you cant move on to the next possibility
Right?
And you also ignored Stelteks good info
http://maximumpcguides.com/windows-7/disable-usb-selective-suspending-in-windows-7/
http://www.tek-tips.com/viewthread.cfm?qid=1580050&page=9
http://answers.yahoo.com/question/index?qid=20100108194915AAsbpTc
http://www.vistax64.com/tutorials/63567-power-options-sleep-mode-problems.html
Edit: My suspicion is that since everyone of these event 51's that have a drive listed in the error is always with a "/D" at the end even tho that has no connection to any drive letter, that it possibly means disconnect(ed)