Hello, Nussic,
It means your simulation diverged. It can be several reasons. Boundary/volume condition settings could be one of possibilities. Also, if you run a transient simulation, your time step can not be too big.
I'm from Simerics, the platform behind Creo Flow Analysis is from us. We can help you out very quick but we need more details about your problem and settings. If it is possible, can you share the case to us? Thanks.
