Go to the RadWindow example 'Returning Values from a Dialog' and modify the DeafultCS.aspx file to add the following lines BEFORE the <qsf::footer ... tag.
Add a total of 180 rows of data to the table. When you view the page what you should see is that most of the page has the grey background but you can' tsee any of the content. Additionally if you mouse over some of the elements you will see content show itself briefly.
This bug only appears to occur on IE7--Firefox 2 and Safari 3 seem to be ok.