My game keeps crashing every now and again with a critical error and now I can't even load the game it just crashes with the same error.

negative delta time

history:UGameEngine::Tick <-update world <-main loop

Looks like a glitch in the install of the dame to me. I would try to completly uninstall it, also make sure you delete any saved files that the uninstall might not take out, and try to reinstall it fresh. Let me know if it works!

-Cody