1) are you playing the latest vanilla version of the game? That means VC 2.036, with no mods/tweaks/cheats. If yes, go to 2
2) post your rgl_log.txt (found on game folder).
3) post a link to download your savegame (Dropbox, GoogleDrive, etc)
4) post your computer info (your OS like Win10 64bits, Ubuntu 17.10, etc)
5) describe your game/campaign (storyline or sandbox, what you were doing, etc)
6) a screenshot of the issue if possible. You can post it here: https://tw.greywool.com/i/
7) post your rgl_config.txt (found on your /Documents folder)
devs need that kind of information to check your game.