Upgrade to 7.08 - Error 404

Hi,

I have just done an upgrade to 7.08 and I intend to do them all but the ads are now not working. They display on the index page but then they all link to 404 - page not found. Can anyone help please?

Thank you :) 

M

Did you check the main .htaccess file?

Thank you for your reply.

Where would the main one be and what is it meant to say?

Thank you :)