Downlds refuse to reload (click on link)
Let us know if it keeps happening. It's a rather risky approach you have. And keep a backup of the downloads.dat & .bak files somewhere else also.
With LW 4.12 you should be able to resume from Library window incomplete folder & they will continue from where they left off. That's using the Resume button.
Perhaps you moved the incomplete files out before LW had properly closed. Task manager will let you know if LW is fully closed.