if you are hosted in medium trust you need to use our medium trust configuration you could start with our medium trust package, which is pre-configured for medium trust.
The only difference with our medium trust package is the web.config file has some differences and the AjaxControlToolkit.StaticResources.dll is deleted from the bin folder
So if you used the non-medium trust package you should update to use that web.config file and delete the dll mentioned.
Hope that helps,
Joe