I have actually heard of people deleting their DLC but this is regardless because people with or without the DLC get this error. It's in the software programming and not whether or not someone actually has the DLC. I have the DLC and I never got the DLC pop-up. I got a different kind of 'corrupt' save problem.
I deleted the DLC (hell, the whole game, and all savefiles), then started from a "good" (ie. working) savegame. Still got the error.
PS: Loading the "good" savegame (which has 23 hours of gameplay with the DLC) obviously yielded a warning that DLC was missing, but the game still loaded and played. The error I'm talking about is the inability to load any savegames made after that point.
Also, I have tried loading a "good" savegame, and just replacing that single file, without using autosave or creating new saves. Still got the error.