If you are not hosted by Blackbaud, look into the following:

1. Logon to the NetCommunity Server
2. Try to pull up the website from the server
3. See if you are able to get a more specific error
4. Go from there
(One example of a specific error may be "System.IO.IOEception: There is not enough space on the disk"
If you get this, then go into My Computer and see how much disk space is available. Start freeing up space. An additional 50mb can make the difference between a site being up or not)