Thank you for the question.
In regards to RadTabStrip, the selected tab depends on the last tab item where you have placed a control or where you have modified the size/location of a control. You can set the selected tab explicitly by setting the SelectedTab property programmatically just like you did.
I would suggest using RadPageView
control instead of RadTabStrip. The item that you will get selected with RadPageView is the one selected at design-time. Please note that RadPageView was introduced in Q2 2010 release, so you will need to update your Telerik version. In addition, the new Q3 2010 released two weeks ago contains many improvements and fixes throughout the whole suite. You can refer to our Release Notes
for additional information.
Should you require a quicker response, you may consider purchasing one of our licenses. The support tickets that you submit from a licensed account are reviewed with higher priority than the regular tickets and the forum threads. For additional information about the available support options, please refer to this link
Should you need additional assistance, feel free to contact us.
All the best,
the Telerik team