Game saves can be corrupted by several things... the main problem I used to have was adding or removing activated mods, and then trying to use the Save from a different game configuration. Even little changes can cause issues that may not be readily apparent. The 2nd thing I used to do, was "shell-out" to Windows while playing. The game, being an old WinXP build, expects uninterrupted, "exclusive" use of the video and audio streams. A third one is incompatible mods being used together. The game's engine is "robust" in the regard that it can be difficult to crash it sometimes. However, it has no error-catching, and gives you no clue (usually) when it runs into a problem. You might see symptoms, like what you encountered, and it will attempt to continue running, until it just falls on its face and can no longer comply...
