Hi all. We're starting to install and launch our new site with Umbraco, and we're running into some strange errors. If I browse to Settings > Document Types, then click on Master or any of the other doc types, I get this error:

Object reference not set to an instance of an object.

[NullReferenceException: Object reference not set to an instance of an object.]
   umbraco.controls.ContentTypeControlNew.setupInfoPane() +962
   umbraco.controls.ContentTypeControlNew.OnInit(EventArgs e) +258
   System.Web.UI.Control.InitRecursive(Control namingContainer) +132
   System.Web.UI.Control.InitRecursive(Control namingContainer) +420
   System.Web.UI.Control.InitRecursive(Control namingContainer) +420
   System.Web.UI.Control.InitRecursive(Control namingContainer) +420
   System.Web.UI.Control.InitRecursive(Control namingContainer) +420
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeSt

Also, the Media Types folder is completely empty. I'm not sure what's going on, or how to correct the problem. Any ideas? Thanks for your help!