Bizarre Internet Wobbles

It's 8:43PM here, and about three minutes ago, I went from uploading 1.3MB/s to .2KB/s and all the trackers are not responding. I wonder if my ISP has something that blocks off some ports starting automatically at 8:40PM (the beginning of the really peak usage times for the Internet) or if it's something else. Here's a graph showing what it looks like.
If you're wondering about those last few spikes of red, it was probably ghost throughput or something from a couple last things sending that had already mostly finished. I don't really know. It's 8:51 now and I'm currently at effectively 0K/s either direction, except for browsing the web. Strange, isn't it?

S'ok, my hard drive needs a break. As you can see, I transferred over 100GB today.