I am not able to reproduce the problem using IE 7. It can be reproduced if you click too fast between tabs in FF or Chrome browsers ( it is a bug), but it shold not occure whent the page has been loaded. The problem is related to binding of RadGrid and getting the content items.
I have tested using Sitefintiy 3.6 standard edition build 1936. If the problem persists send us your project for debugging. You can open a bug report with 20 mb attachment allowed or provide us with an external link from where we can download the project. If you have live link to a dev server you can also send it to us.
the Telerik team