I think your problem is with Xolox's synchronisation of file segments - it overlaps the last 2K of every segment with the first 2K of the next segment (excluding the first and last segments of course). If the segments don't match, the part is dropped and downloaded again - unfortunately, if xolox drops the wrong part (ie the correct one), you will end up downloading the same segment incorrectly over and over again (i.e it will never match). Your best bet is to download as much as possible and put the segments together yourself (using a hex viewer or similar, in association with the resumeinfo.txt file which will tell you where each part belongs).
Hope this helps (I've had to do this myself with several files).