Thank you for your reply.
Yes, I was talking about using run on scene option used for preview.
I don't acess anything via scripts, just using actionparts and either browsing to destination [Browse link...] or using drag and drop "lasso thingie" to chain things together.
Definitely not a memory issue, as it's easily fixed by renaming scenes. As I mentioned, I believed that VS assigns unique ID (not a real "name" but rather a "table adress") to everything (conditions, values, scenes, and so on) and naming serves only as a guide for developer "(since "Rose received?" is more informative than F240 or whatever engine ID's look like).
Anyway, after discovering the problem I renamed scenes to Lucy(Dialogue), Lucy(Closeup), Lucy(Quests) and so on and it works just fine. I definitely start to use individual names from now on, just to avoid any similiar problems in future. Still it's kinda weird that "engine confusion" when using "run on scene" seems to be somehow linked to the amount of scenes in the project.