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Generell possible solutions:
1. Make sure that no additional mods are installed or activated.
2. Check the integrity of game files:
https://support.steampowered.com/kb_art ... -QEUH-3335
3. Don't use ALT+TAB during loading screens, to click on a different display. It might take a long time for the game to load, even when it seems like it might already have crashed (mouse cursor becoming a circle or might be missing entirely).
4. Make sure your anti-virus-program, windows defender or firewall are not blocking the Enderal Launcher.exe, tes5.exe and skse_loader.exe. Furthermore make sure they all run with admin permissions. Make sure that Controlled File Access is disabled.
5. ENBoost and OneTweak can cause the game not to start on certain hardware configurations. Try to disable them in the Launcher.
6. Don't launch the game using the skse_loader.exe, start it directly through Steam or the Enderal Launcher.exe.
7. Try restarting Steam and/or your PC.
8. Change settings in the Enderal Launcher, make sure the CPU and RAM usage are maxed out in the optimization tab.
9. Try redownloading the game.