Every so often, YWS hangs up for about 15 minutes to 30 minutes. I think this happens only once a week, though it may happen more than that. At any rate, if you encounter it, what's going wrong is the Yahoo Bot. Despite Yahoo outsourcing all its search to Bing now, the Yahoo Bot for some reason still crawls YWS. And when it crawls YWS, it goes bananas. For some reason, it starts trying to open tons of pages at a time. This in turn slows the site to a crawl for the rest of us.
By the way, this also happens with the Bing Bot as well, and for the time being, I've banned the Bing Bot from YWS. Also, if YWS hangs up on you and you're trying to submit a post, do not re-submit the post! Your original one will go through; usually even if you close the browser (though I wouldn't suggest closing the browser/window until you've received the confirmation message).
