I had a very similar problem with Office 2016 failing to open after a restart. I eventually tracked it down to Microsoft office click-to-run service being disabled. After turning off the sleep command for office and microsoft visual c++ in Cleanup the problem seems to have disappeared.
The direct solution was
Win + R to open run dialog
Enter "services.msc" and run
Find "Microsoft Office ClickToRun Service"
Right click it, select properties, set to start Automatic.
Click Apply and OK
Right click again and select Start
It seems that Cleanup was disabling Click to run each time I closed down.
Avast should really sort out this problem.