I am also having problems getting connected to the torrents (only 2nd time in 6 months) I have downloaded but this problem as well as connecting at LW opening seem to go away on thier own. I have tried using Utorrent and other torrent clients and thier download speeds are atrocious. LW might be unreliable but on the DSL line I currently have I get almost the max upload speed of 350 kpbs compared to Utorrents or bit torrents 3 to 10 kbps on a good day.
Simplest way to make whatever torrent client your default is to open that client and download and open torrents from there. This doesn't really make it your default client but if you download torrents using LW it becomes a Limewire torrent ( check a torrent you've downloaded with LW and it reads LimeWire Torrent) and that is why the torrent opens LW automatically.