I wonder if your LW downld preferences are corrupt!?! These are the files called download.dat & bak in your incomplete folder. If you're starting from scratch, you could do what you do with deleting from downld list, then clearing them from the incomplete folder in the LW Library window & then close LW. Then check to see if they're there after you've gone to physically look at the incomplete folder itself. If yes, then only the downld.dat & bak files should be there. Delete these! trash them! Then open LW up again. LW will create new ones when you start to downld again.

According to the developer, it's ok to close LW & go to the incomplete folder & delete/trash the incompletes you don't want. I'm a bit wary of this though in case it corrupts the downld.dat downld preferences.

Run your computer over with Disk Utility to make sure there's no directory damage. You may need to start from the OSX startup disk to do this.