I wish you had made it much simpler, in terms of actually how to use the mods people download on here. It can not be expected of everyone to understand these terms, as I certainly do not. I don't understand what $INT$ is, even from a google search, and I certainly did not see this alleged folder anywhere in any of the versions I downloaded. I could not use a single mod I downloaded, after spending about 2 hours looking for how to do it. The guides are of no help and neither are some of the replies. I am giving my rating because, while it may be a good loader, It is terrible in terms of user-friendliness so much so that I do not plan on touching it until I see a reply that gives a clear answer as to how to use the mods present within this community.
I have not heard about this issue before. It sounds like either a bug or the antivirus randomly deleting a file (common with avast/avg/norton). If you make a post on the SDTL forum thread (link at the top of this page) with some additional information I can try to help you out!
When does the error appear? Does it say anything else (along the error)? Does a fresh download of SDTL2 work? Are you running the game from a shortcut or a console?
Feel free to include any other information that you think could be relevant!