said by bbear2: I've done several searches on this and the suggestions seem to be all over the board in terms of the cause.
The hibernate process is pretty simple. Everything in memory is dumped to a physical file on the system. When the system resumes that file is paged back to memory.
The issue you experiencing may not be tied to a particular issue thus the results you are finding. Instead it could be a symptom tied to other specific problems.
said by bbear2: I'm looking for some guidance as to what might be the "most likely" cause/solution. This also seems like finding a needle in a hay stack.
There isn't a single answer to this problem as you have already discovered. Troubleshooting will be required.
Check event logs for hardware issues?
I would eliminate the OS from the equation if I found that turning it off & back on as already suggested didn't help. This can be done in one of many ways. If you find that the issue occurs regardless of the existing OS then you can be looking at a hardware issue. It's almost assuredly something with the OS though.
BIOS, drivers, etc, would be a good place to start too.
Since I have the capability, I would honestly throw a different hard drive in & reload the OS to see if the problem is still there. You could use a Live OS as well but hibernating a Live OS has its own issues since it requires non-volatile memory space (hard drive, etc). You may be able to use a flash drive in a pinch.