Which forums have you tried? best place to post questions specific to Unreal Tournament is UT forums here. reason is that answerhub is geared towards bugs and questions related to Unreal Engine, not any specific games. We do answer what questions we can here, however best possible solutions for Unreal Tournament will probably be found on UT forums. If you have a UT Editor question it can be answered either on forums or answerhub, however it is still preferable to keep them on UT forums in bug reports>UT Editor section found here as we have UT specific staff that checks into that section.
Having said that I’m more than happy to try to help you. Can you post a copy of your dxdiag here? Additionally what specific actions are you taking before this crash occurs? If you open your task manager, do you see any spike in amount of memory being used by game?
Additionally, can you post your logs here? They can be found at UnrealTournament\Saved\logs\ in filepath that you saved game to. Finally, try deleting your saved folder in same filepath and try again, do you see same crash occurring?