a 403 error on MS IIS is means that the permissions set for the root directory (default website) have been set to deny accessing any directory directly and listing the file contents. On poorly protected/set up servers it is often possible to view the 'root' and sub directorys.
What this acutally means is that the file in the default folder - the website - called index2.htm is not publically viewable. Therefore when you try to view it, it fails and denys you the ability to view the directory's contents.
The more common error is a 404 - page not found - this is when the page you are looking for does not exisit.
I would say that either they have not paid their bill, and the server has reset the site permissions or that they have set it. Depends a lot on the hosting set up. You could try backdooring it - like contact.htm or index.htm - it is not normal for a site to used index2.htm as the default page.
Out of the box a URL say
http://www.apple.com is in all truth
http://www.apple.com/index.htm or index.html or default.htm or default.html or the same but using .asp or .php as the suffix, depending on the server set up.
There will be a test.