Please confirm you are using Frostwire 5.1.5
What is the path to your Torrent Data Save folder? (Tools > Options > BitTorrent > (Basic) > Torrent Data Save Folder)?
Are you just downloading complete torrents or are some partial torrents, and do the problems exist with Full or partial Torrents, or both?
Please do not Private Message me with questions that can equally well be posted in the forums, and may also help others. Do use the forum search.