404 Not Found when Logging In

Running WP 2.6.2 at childcare.mantuaschools.com
Install went smoothly. However, when I try to log in, I get a 404 Not Found page after entering username and password.
The following error message is given:
The requested URL /home/mantu0/public_html/index.php was not found on this server.

The installation is at childcare.mantuaschools.com and I’m not sure why it’s trying to look for a page at the site root and not in the subdomain. Although it gives this error message, if I then go back to the main childcare page and refresh, the site sees me as logged in and I can get into the admin console by clicking edit on a post. Unfortunately, leaving it this way is not an option as I’m creating it for our school child care program and they need to be able to get in without jumping through hoops.

Any ideas on what is causing this problem and what I can do to fix it?

Thanks
Meri