Simulation Failing after ~100 iterations...help?

Hi Everyone,
I am attempting to run simulations of a open wheel race car rear diffuser (specifically for FSAE), I have designed it in SolidWorks and imported the body in a STEP file. Since the body is symmetrical, I am only running the simulation on half of it.
Since this is really my first experience using this program (and CFD in general, with Solidworks Flow Sim being my only other CFD experience), I am using the various tutorials to really try to teach myself how to use the program. With that said, Once getting the geometry set I loosely used the "flow over a Co2 dragster" tutorial to guide my setup. I had the mesh generate with no issues, and ran the simulation. After around 100 iterations the simulation stopped and I got this message

Warning:
volume_2 [www.19875.5] RANS Flow: Failed
Solver singularity: smoothSolver: Solving for omega, Initial residual = -1.#IND, Final residual = 1.#QNAN, No Iterations 100

(sidenote: is there somewhere that has failure codes/explanations?)

I had changed a few accuracy settings and tried again and got the same result. I tried to regenerate the mesh and had no success...does anyone have any insight? Any help would be much appreciated! (I would be happy to upload any files that could help figure this problem out)

Thanks!

Single Volume and Mesh Issues

Is your volume a single volume, with your car subtracted from a larger box as in the tutorial "Flow Over a CO2 Dragster"? It would probably be easier for you the create this flow volume in Solidworks.

The most likely cause of the failure you are seeing is a mesh problem. There can still be issues with a mesh even if the generation process didn't fail. I suggest you review the FAQ "How do I fix mesh and solver failures?".