I'm having the EXACT same problem. However, this is after installing NMM and FNV on a new SSD and a new OS. This is probably the problem for me. This might help. When I try to debug the program after it crashed saying "NMM has stopped working, windows is checking for solution to the problem", it says that: - An unhandled Microsoft .NET Framework exception occurred in NexusClient.exe So there might be the root of our problems. I'm trying to uninstall and reinstall .NET Framework since yesterday though. Didn't work.