I think I have read every post here (and elsewhere) on this issue. And after adding them all up, everything is finally working for me.
The permalink plugin puts an extra line at the beginning of the XML file and causes RSS feeds to report an error -- and not function.
Deactivating the permalinks plugin will cause all subsidiary pages to go into endless loops...and not load. It's a conundrum.
With the permalinks plugin activated. I changed my permalink setting, in the dashboard to DEFAULT (you get some scary pop up message -- ignore it).
Then deactivate the plugin and suddenly everything works!