well make sure to get all the par2 files available for. that 100% number only indicates, that this post was complete at the time when it was posted and on the server that was used for indexing. i remember there is a programm called something like nzbchecker, with which u can check if an nzb is complete on your usenetserver, but checking every nzb befor downloading is to much of a hassle to be worth it in my eyes...