LW does have a function of auto-checking to see if the files will find & connect to hosts. It does this perhaps once every 30 or 60 mins. It's my guess, when either this or Fixed Stalled is used, LW attempts to connect only to the hosts it was downloading from previously. If that's the case, then these hosts might not be online at the time or their ip's (dynamic ip addresses) may have changed in the meantime. That's why it's always best for the user of LW to manually re-search for the files themselves so fresh hosts with the same files ('identical' download hash) can be found.