I have been playing GMod for a while now yet I have never had this problem. As you would do in GMod I would load it up, then select a map to play, yet on certain maps GMod won’t load them. To go into details when I start loading a map it would be normal, but when it gets to ‘Loading Resources’ It would simply return to the main home screen. Worst part is this has happened to one of my favourite maps, and I desperately want to play it. I will try reinstalling GMod but other than that, I don’t know what to do. One last thing, I don’t know if it has to do with the map itself but I’ll give it anyway: rp_necro_forest_a1
Best bet is to post the crash dump.