If your computer consistently crashes, then it'd probably be wise to backup your downld preferences. Go to the incomplete folder & find these 2 files: download.dat & download.bak & copy them to somewhere else on the computer. Make a practice of this every day. So then if your computer crashes whilst LW is open, replace the 2 download.dat & bak files with the copies. Then LW should recognise your previous efforts. In fact, it might be wise to do this a couple of times a day. Sounds laborious but at least it will be effective & your downld efforts won't go to waste.
As a one off effort, it might also be worth deleting your LW Preferences folder whilst LW is closed; instructions here:
Fixes for Limewire I don't know if this plays a part but doing so might help t freshen up the main preferences. Just remember your settings such as where your downld folder is (or write them down.)
* A better solution to this problem with corrupted downld preferences will eventually be needed to be found. This doesn't seem to happen on a mac.