I had to edit the original post. Solver.xlam and other xlam files won't start anymore. The issue started with this awful Windows update as per info below.
I have tried quick repair and full online repair without luck. The files are in trusted folder location. I am at my wits end. This is the worst update issue I have seen since Windows Vista.
Windows 10 Pro upgrade from OS Build 16299.125 to OS Build 16299.192.
Update ID: 2018-01 Cumulative Update for Windows 10 Version 1709 for x64-based Systems (KB4056892)
Any help is appreciated.