If Auto-solve is being checked for a Case after one or a few geometry updates, it might happen that the Case becomes invalid. GoSimulate will notify you about this by showing a warning dialog, as well as drawing the invalid Case(s) in red and striked out.
The following image shows such a situation. Note that the transparent brown geometry representing the boundary condition no longer matches the underlying face:
As the dialog will tell you, there are two options here. Either you can edit the Case in order to replace the invalid faces, or you can uncheck Auto-solve. If you leave Auto-solve checked and continue updating the geometry, no more warnings will be given.
To fix the problem, locate the problematic boundary conditions (in this case under the Thermal tab). Then delete and replace the invalid faces. You might also delete the boundary conditions altogether.