I believe this is happening because there aren't enough hosts.
try searching for it again but make shure you don't dowload the exact same file. also make shure that there are alot of hosts for the file it should say this under "hosts" when you search their speed is also important and can be found under "speed".

you can also try to keep downloading the file and so no progress is lost go in tools, options, savings and at the bottom there is something saying days to keep incomplete files, there just right how long you'd like it to keep the files. this has a big role since after the file has been there for a week it goes back to zero