Your website is set to use .NET 1.1. It should be set to use .NET 2.0. If you have access to IIS Manager on the server, you can change this by opening the Website Properties, selecting the .NET tab and then selecting the correction version. If you do not have access to IIS Manager, you will have to have access to a control panel provided by your host or your host will have to change it for you.
Also, .NET 3.5 SP1 should be installed on your server as described in the hosting requirements.