Oh yeah,
Rangsk brings up a good point. Not too long ago (a couple of months, maybe?), the bit torrent protocol changed (probably to improve network scaling) but this caused older clients to not work so well (although they do still work). I don't recall which version this happened with but it's possible this is your problem,
k1ng.
Personally, I like
ABC but, again,
Rangsk makes a good point when he says that you should find one that best suits you...