It seems the feed problems are not going away. As far as I can tell, Feedburner is deciding that the feeds being served by this site are far too slow, and so it gives up trying to update.
Now the actual feed is working, so I’ve removed the automagic redirect to Feedburner and changed the links in the sidebar so that they point at the actual feeds rather than the redirected Feedburner address. So anyone connecting directly to my feeds should find that service has been resumed, and anyone who decides to subscribe now will get an up to date feed.
On the other hand, anyone subscribed to the Feedburner address will be getting some breakage, but I’ll try to fix that with some .htaccess trickery.
It does mean that I won’t see any statistics on how many people are reading my feeds, but I can live with that.
 Well, subscribed to. How many actually read this stuff is another question altogether….