Outlook web access no longer works

Hi I hope someone can help me with Microsoft Small Business server 2003.

I had to restart the server today because it was really slow and then completely locked up. Upon restarting everything worked fine except for Outlook web access. When I try to access it I get the error:

Internet Explorer cannot display this webpage
This problem can be caused by a variety of issues, including:
• Internet connectivity has been lost.
• The website is temporarily unavailable.
• The Domain Name Server (DNS) is not reachable.
• The Domain Name Server (DNS) does not have a listing for the website's domain.
• There might be a typing error in the address.
• If this is an HTTPS (secure) address, click Tools, click Internet Options, click Advanced, and check to be sure the SSL and TLS protocols are enabled under the security section.

It worked absolutely fine before I restarted the server.

Does anyone know how I might resolve this?

Many thanks for your help