Why am I Getting Pmmain, Program Error, or Main Program Message on simulation?

When the model is simulated it crashes ProcessModel at 312 hours, displaying any of the following error message:

Reason

There are 24/7 shift files in use.

Solution

Having 24/7 shift files is the same as not having a shift file at all. Remove the shift file reference.

Main Program, Windows is checking for a solution to the problem
Main Program,
Windows is checking for a solution to the problem