@Chrea Great suggestion.

I have interrupted their operations so much over this that I need to progress after hours. 

The disruption of having QB Support OTP with me while I have everybody off the company file(s) is something they are getting a bit upset about.

As always, these errors pop up without any updates, upgrades or anything, and plague the customer for days/weeks. And in the end, like I said, QB can offer no reason for the failure, which is the correct fix 'next time', or even a "to avoid this in the future, be sure to ...". 

For this reason, I will have to wait until tonight to do anything on the company file, after they close.

That is when I will do as you wisely suggest!

Thanks!