What's up with my torrents?

Can someone explain to me what's up with my torrents? I use Azureus, generally, but sometimes I try TorrentStorm.

Anyway, I was online yesterday, happily downloading on Azureus. I had a speed of 27 kb/s or something, which is about the best I can hope for, realistically on my 256 ADSL. Anyway, I shut my computer down a bit later on. The next day I booted it up again, loaded up Azureus, and now, for some reason, all of my torrents show a red smiley face, except for one, and on that one, despite the fact that there are the same number of peers and seeds online, I can only get a speed of 1.5 kb/s. I can upload allright - in fact, it's uploading away quite happily. Checking the details, I see that all of the peers apart from 2 are choking me, even though I'm uploading to loads of them.

What's going on there, and how can I get back to my normal speeds? I mean, it's not as if I've changed any of the settings. In fact theyr're exactly the same as before. The strange thing is, I tried TorrentStorm, with some different torrents, and I get higher speeds on there - but only about 8 kb/s. What's going on? I've tried leaving it. In fact, I left it all night, and when I came back, although I was connected to about 10 seeds and 40 peers, they were still all choking me apart from 4 (and those four were hardly giving me great speeds - less than 1 kb from each).

Has anyone else had this problem? And, if so, why, and how did they fix it? Thanks a lot.

The other thing is... now lokitorrent had gone, can we still use their trackers? I mean, I have one torrent that I'm half way through downloading, and it's on a loki torrent tracker, and it seems to still work... sometimes. Is that okay?