Comment 39 for bug 276990

junior, if you unload iwlagn then cfg80211 then mac80211 it will work. Its a dependency issue with the modules. However the modules get rewritten right after you use the sudo make install command. The only reason you don't see the effect immediately is because the old modules were read in during the boot up sequence and are stored safely in the RAM. If you restarted then it won't make a difference if you reload those modules.

I will test my machine with a lot of torrents at once later today to see if I can reproduce the issue though.