I am a regular user, running WordPress on many sites, I have installed WordPress 3.1 without a problem for a new client.
Upon accessing the site to check the new theme I only see the directory listed in the browser, a list of all the .php files in the folder.
I have installed in 'domain.co.uk/folder/' and am running Twentyten to test the site before I start creating the client's theme.
I have no plugins installed that could be interfering. Any advice appreciated,