Hi Joe, Yahoo Pipes turned on a cap for their service, so if more than 200 requests are received from the same IP address within an hour, it will start returning a 999 error for that pipe for the next hour.
For some reason, our instances of feed manager on the library site seem to be tripping this, although we have the cache time set to 15 minutes. I asked our library's webmaster to up the cache time to 60 minutes, remove our local RSS feed for the feed manager, and take down the feeds until Yahoo clears the 999 error for the pipe, so we can try again.
The problem I thought should perhaps be addressed or worked around is that in looking at the system log, it seems once an RSS error is returned to feed manager, it keeps attempting to load that RSS feed on every page load by every user. Of course, that means that this particular error will never go away, because between bots, etc., we're definitely getting more than 200 hits per hour on the home page of the site.
Would it be difficult to change feed manager so that it respects the cache time, whether an error was returned or not? Maybe this should be done via a system key, since some people may want it to constantly poll if an error occurs.