In an earlier post, I mentioned an error to auto-upgrade Wordpress 2.7 to 2.71, the reason is the problem of the free webhost byethost.
If you use byethost too, and need to update, here is the easiest way.
Backup your files and database. Of course you can use FTP to download all files to your local computer, but quickest is to make a copy in the server itself using Vista Panel File manager tool. Export your database, and save it as a file, just in case something go wrong during your update.
Delete wp-admin and wp-include, do as the instructions given out in the Upgrading Wordpress document.
Use Fantastico type installer to install the latest version of Wordpress. Byethost almost has the latest version of Wordpress as soon as a new version released. This save you a lot of work to download and unpack and upload to your server. Don't do the wordpress installation procedure.
Then go to File manager, copy all files except for wp-contents and wp-config and overwrite your old files.
There are no database upgrade from 2.7 to 2.71, so update success!