Can you exit to the main menu and then load? Or just load from the main menu when first starting the game?
Does it make a difference playing in singleplayer, rather than co-op?
Please email supportdos@larian.com, with a description of the problem and the report.zip file generated by the
D:OS support tool (for the PC version). The report will contain your saves; if file size is an issue older saves, or ones from other profiles/sessions can be deleted. Hopefully that will let Larian track down the source of the problem, and it can be fixed, prevented, or possibly the loading process changed to be able to handle whatever the problem is.
