2010 Duramax no crank no start

Were are you at?
If it is losing communication with the Vehicle security module then it could be the IGN switch, or just something throwing the program loopy. Check all the fuses with an ohm meter or test light when it does it again. You could be losing connectivity when it is warm. Does the bus have an alarm on it or possibly a saftey switch that will disable it?

Is there any common factors with the weather or anything? It sounds like you may just have a loose connection. I have no Idea where the security module on a bus Is. I would assume it would be in the relay center. I know the Duramax trucks security is part of the ECM programming.