It could be A LOT of things!
Check the details of the message , what does the Mod name point to. Which file?
Or check it in event viewer in Control panel> Administrative tools >comp management.
Does it happen with ANY file and folder? Or with, let's say... only folders that contain videos, or only microsoft office files?
It's important because it could be hard, or it could be easy, change some settings, having to do a regsrv, delete a file, bla, bla, bla...