virtualbox.org

I see 4 log files (vbox.log, vbox.log.1, .. vbox.log.3) and at the top of .log.3:

VirtualBox VM 5.1.18 r114002 darwin.amd64 (Mar 15 2017 16:25:52) release log

At the top of .log.2:

VirtualBox VM 5.2.6 r120293 darwin.amd64 (Jan 15 2018 16:23:36) release log

I looked in .log.3 but couldn't find any text like "value="

Would there be anything somewhere in .log.3 to say I applied a 5.1.x patch?

From my Snapshots folder:

Rosss-MacBook-Pro:Snapshots rwaddell$ ls -alR
total 1265688
drwx------ 3 rwaddell staff 102 25 Jun 2017 .
drwx------ 8 rwaddell staff 272 24 Jan 18:57 ..
-rw------- 1 rwaddell staff 648028261 25 Jun 2017 2017-06-25T18-28-28-799899000Z.sav
Rosss-MacBook-Pro:Snapshots rwaddell$

Reverting to 5.1.28 (plus extension pack) - worked; I was able to start up the guest and shutdown Windows normally. I upgraded to 5.2.6 and all is well.

Thanks everyone for your excellent help!

RossW wrote:at the top of .log.3: VirtualBox VM 5.1.18 r114002

So, you don't keep up-to-date after all. Your last version seems that it was 5.1.18. That might be too far from 5.2.6 to make this worth looking at. Further proof? Opening the saved state with 5.1.28 worked, even though you saved the state with 5.1.18.

RossW wrote:I looked in .log.3 but couldn't find any text like "value="

That was supposed to be in the ".vbox" file, not in any log.

Glad you got it going. Marking as [Solved].