Sounds like you've got pages stuck in the umbraco cache somehow (possibly bad file permissions, but let's try the easy thing first).
In the Content section of umbraco, right-click on the top-most node and select the "republish site" menu. Once that's done, see if you're getting the same behavior.
If you are, then right-click on the top level nodes, one at a time, in the Content section and select the "publish" menu. Be sure to tick the 'publish children' box. Repeat for each of the top-level nodes in your content tree. Are things working now?
If it still isn't working, let us know. Probably a file permission issue on the /data/umbraco.config file.
cheers,
doug.
MVP 2007-2009 - Official Umbraco Trainer for North America -
Percipient Studios