I was just downloading a torrent on Utorrent, and it was going about 400kbs and all of a sudden slowed down to 0.1 - 0.4kbs for no apparent reason. I don't know much about torrents, so can anybody help me? Does it have something to do with availibility or seeds (because there are 0 seeds)
Yes. Torrents work by many peers having part and/or all of the file you are downloading. It can then source chucks of it from different users online. If there are no seeds then there is no single user with the complete file online.
Many other things affect torrent speeds, such as upload saturation of the other users, etc.
You could read more on torrents:
While availability of Seeders and Peers is all important (and seems to be the issue in your case) it is also worthwhile considering if your ISP throttles torrents. Some ISP's throttle torrents between peak times, e.g BT in the UK throttle torrents after 6pm on weekdays and at weekends.