Hi Brian Doner,
I reloaded the page where in RadWindow is opened a page with 5 sliders(with different values) about 20 times, but I am still not able to reproduce the problem you mentioned.
It is a shot in the dark, but I would suggest to set the the RadWindow property ShowContentDuringLoad to true and see how your application will behave.
If this does not help you, please open a new support ticket and send us simple running project, where we can observe this issue. We will check it right away.
the Telerik team