Have you tried to close LW and exit and then re-open it?
After files have reached 100% they usually should start to verify the contents (i.e. comparing them with their respective hash trees) to see whether they have completely downloaded. If at that time the host of the file goes offline, you might have to wait till they come back online.
Did you check in the incomplete folder whether the file size of the file has reached it's supposed maximum? I actually had this once; the file downloaded completely but didn't move to the svaed folder. I then just closed and exit LW and moved the file manually.
