First step: re-upload the “wp-settings.php” file to your host, overwriting the existing one, as that seems to be the common thread in both of the errors you’ve posted. On the other hand, I think that file gets called from every page, including the regular “index.php”, so it should be causing problems all over the place if it’s goofed. But try it anyways, maybe the file got corrupted. And if you’ve already done this, then re-download WordPress and upload the version from *there* instead.
Second step, start deactivating any plugins you have, 1 at a time. One of them could be causing the error (I had that problem with a misconfigured plugin once).
Good luck and let us know how it works out ??