This is browser-specific behaviour when window.location.reload() is called. It cannot be avoided as far as I know. If you can find a workaround and share it with the public we will all appreciate it.
On selecting the fifth tab - you can pass a hash tag and parse the URL when the page is loaded to select the desired tab.
Another option is to prevent the full reload and only initiate a partial postback that will refresh only the data you need.
All the best,
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed