User Authentication Required?

[m0m0y0]

So certain torrents from the site suddenly have an error message in my download manager, stating that user authentication is required. I don't know why this is, because some of the affected files are already downloaded, i was seeding them, but it's only around 10 or 15 files. I don't know if it's a problem with the torrents, or if it is my download program, but any assistance would be greatly appreciated.