Hi Chris, (may I call you Chris? :P)

I found out several things since my original report. The libtorrent version is indeed 0.14.7 as you said (I wrote that bug report at 4 in the morning and was not only tired but also distracted on IRC). However, that version came from my distro and I suspect there's something wrong with it. I then went and grabbed the 0.15svn one from the front page of qbittorrent where it offers a link to it. Before compiling it and then compiling qbittorrent, I removed all instances of my distro's libtorrent. The compilation went for both just fine and when I open a torrent it starts to preallocate (I see lots of disk activity) so that seems to be fixed for me. BUT, after preallocation is done and it starts downloading, half a minute later or so, a message pops up and says there's something gone wrong on the disk IO side and immediately halts the torrent. I tried with three other torrents and get the same behavior. So then, I decided to grab libtorrent 0.14.8 and compile it, together with qbittorrent again but before that, I removed everything related to version 0.15svn from libtorrent. Compilation again went fine for both libtorrent 0.14.8 and qbittorrent 2.2.0beta2 and all seems to work now, including preallocation. After trying out a few torrents which carried only a single file, I tried out a torrent which carried three big files in it. When I opened it, I selected to download only the first of the three files but I noticed after clicking OK, it went on to preallocate *all* files - I checked their sizes too and it also took way longer to preallocate even though I selected only one out of the three files... the way I know that is because I compared how long it takes to preallocate the selected file against another torrent which carried only one file but of exactly the same size. The torrent with the multiple files in it where I only selected the first one to download took way longer to preallocate (in total, that torrent carried a load of 2.1GB, the selected file for download was only 700MB big). I've no idea if this is normal behavior for qbittorrent or libtorrent itself (in some torrent client it is, like Vuze for example) but it is not normal behavior in KTorrent. In there, if the torrent carries multiple files and you select only a specific one to download, only that file will be preallocated and the rest will not show on disk. I find this a better way of doing it for the following reason....

Suppose I have a torrent which is 60GB in size, but I only have 40GB of disk space left over. In case I'd only want to download a specific file from it which fits within my 40GB, this will not be possible because it'll start preallocating the whole 60GB instead of only the selected file in the torrent which fits within my 40GB so in the end I won't be able to grab anything form it because it'll run out of disk space before it even finishes preallocation and starts downloading.

About the trackers thing, I'll have to investigate a bit longer. But from what I've seen so far, both using libtorrent 0.14.7 and 0.14.8, when the torrent has multiple trackers, it seems to go through the list (top to bottom) and stops at the first tracker it can connect to. If there are others after this one, they all display the same massage throughout the whole time the torrent is active, and that message is "Not contacted yet". I'll report to libtorrent bugzilla if needed too...