It can happen that a particular file is difficult to get. Stop it & re-select it to downld from search results. And also re-search it. Trying at another time of day or day of the week or month can also help. Keep in mind that some people are hard to access if you're not sharing more than a certain no. of files. Keep your chat enabled & make sure you're not firewalled in such a way that people can't upld from you.