We were not able to reproduce it on our side. For your convenience I'm attaching a sample video
demonstrating the default behavior we are observing, please do not hesitate to let us know if we might be missing a step in reproducing the problem.
In order to avoid this problem can you please please use Firebug ( it is a plugin for Firefox ) to see what happens when the blank screen appears? Also please check for any JS errors that may come up in the debug window.
Another option for you is to share with us login credentials for the website so we can login to the backend and get a better picture of the problem.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items