This is something that happens when there are alot of hosts with the file you are downloading. Slight changes in each copy tend to build up near the end of a file (especially for mp3 because poeple like to add/subtract data from the 1d3 tags alot). If Xolox downloads a file segment that does not exactly match what it already has (Xolox staggers the segments) it will drop that segment and try a different host. You can turn this off in the prefenences. For media content this is less of an issue, as the file is likely to play anyway (might be a slight blip of something of that sort), but for zips and programs any abnomality can ruin the file.