WordPress Urgent Upgrade
If you have a WordPress site running at less than V2.8.5 then you have security issues.
To know if you have been hacked look at your Permalink structure. You will see that it was odd code at the end and your site links don’t work. Remove the odd code.
Then contact your Database Administrator who will need to remove some rogue Users from your datanase.
Then upgrade as soon as you can.