Problem: 

My domain loads when accessed as domain.com, but not as www.domain.com. 

Solution: 

This is common on our Plesk 7.x, 8.x, and 9.x managed systems, because there's a little check box in the plesk interface for creating a domain that enables the domain to be available as "www.domain.com" as well.  Unfortunately, it's not terribly uncommon for folks to miss that.

If you are on a Plesk 7x-9.x hosted server, simply submit a request to our support team and we will resolve this for you.

For those with Plesk 11, select Hosting Settings and under Preferred Domain you can choose one of three options:

www.domain.tld - this will redirect requests to www.domain.com

domain.tld - this will redirect requests to domain.com

none - this will mean no redirection is in place. So browsers can use either domain.com or www.domain.com