The short headline is that none of the measures you suggested helped. But I gathered some interesting information, and I have a plan. ;-)
Specifically, I uninstalled and reinstalled. No change. I even tried the Repair option. No change.
I temporarily disabled all startups and all non-Microsoft services (except yours). No change.
The first interesting news is that in the course of the various testing cycles, the SP service did automatically start (i.e., on boot) on one occasion! But, alas, the behavior did not recur. This suggests that the issue involves timing and resources. Like something is stealing cycles from your service, so it cannot complete its initialization in the time allowed. Hold that thought.
The second interesting news is that I was wrong about this being the only computer in the office with this issue. In fact, there is one other with the same behavior. That's good news obviously, because now I can focus on what's common to these two and not present on the ones that behave themselves. One such common item is one of my usual suspects: McAfee. But there are some other strange things going on with these two computers, which I will not elaborate until I know more.
So that my client can have the benefit of your backups without waiting for this to be resolved, I intend to put an "sc start shadowprotectsvc" batch cmd in the startup folder. Hopefully there will be enough resources available when that runs. I'll let you know if this bandaid does the trick for now.
Assuming that works, then at my convenience I will continue the troubleshooting, and post the resolution here.
Meanwhile, can you suggest any additional monitoring or diagnostic approaches, given where I'm at? One of the first things I'll try is to use Sysinternals (now Microsoft) autoruns to disable more startup stuff than msconfig is able to do. Any thing else come to mind?
Thanks,
-Earl