I'm having the exact same problem and it just started tonight, within the past few hours. I received notice of a new stable bitTorrent update and the moment I agreed to the update I was stuck at "Checked 0.0" for everything. The closing and reopening of the torrent browser trick described here worked for me to get the existing torrents going, so thanks to the those who suggested that. However that's not a permanent or practical solution,. Hopefully whatever glitch this update seems to have caused can be fixed quickly.