stopped getting any downloads

I was happily pluggin' away with limewire 1.7c, for about a week... getting around 1 out of 4 to 6 downloads. I now have close to 4G of shared audio files that the community is still happily getting from me.
Recently (last night and today) all this has changed. People still upload from me just fine, I always see an upload working, but try as I might, even selecting several hundred files for download, I can't get a single download to work. The downloads either go to "Waiting xs for n reply" and then "Couldn't download", or they hang in "waiting xs for n busy" until it is no longer busy, and then drop to "couldn't download". I know my ip settings are correct and all, as I see people downloading from me.
I have trouble believing this is just the inherant instability of gnutella -- any ideas/ good means of diagnosing the problem?