Go to LW's menu bar, Tools>Options>Speed & disable Ultrapeer mode. This won't be any good for anybody including yourself if your computer is crashing. Also go to Tools>Options>iTunes & disable iTunes importing & sharing options.

If you have over a thousand incomplete files, then it might be wise to weed out those that are at zero %. ie: Arrange files in the downld window by Progress by clicking that column heading & select all those at 0% & pressing cancel. Then go to your incomplete folder on your computer & arrange be size. Delete all those at zero-15 KB. You can find your way there by going to the Library window, selecting incomplete folder & pressing the Explore button.