I had this problem with Firestorm on Windows 11. First start after install worked, subsequent starts got stuck on "initializing texture cache" with the viewer showing a white screen. Deleting the Firestorm_x64 directories under AppData Roaming and Local would resolve it for one restart, but then the problem returns. Excluding the "C:\Users\uwe\AppData\Roaming\Firestorm_x64" folder from anti virus real-time protection solved the issue permanently.